Another Scrambler Purchase/Road Trip - UPDATE- BODY ON FRAME AGAIN

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
Still having me hard to start issue.

Checked some simple stuff first.

Was thinking maybe a crank position sensor issue. I am using a front mounted crank position sensor, thinking maybe it got gunked up.

Harness connector has some cosmetic damage, but no wire/pin damage:

20200905_164553.jpg

I am pretty sure the "front mounted" crank position sensor is the same as the OEM bell housing mounted sensor, judging by the part number:

20200905_164613.jpg

The only difference between an OEM sensor and the Hesco sensor - the Hesco sensor mounting bolt hole is slotted to allow for adjustment of the gap between the senor/vibration damper. No one offers the slotted sensor anymore, so the mounting plate would need to be slotted to allow for adjustment. No big deal.

Picture of the sensor/sensor mounting plate/vibration damper:

20200906_092816.jpg

The gap between the sensor/vibration damper is supposed to be between .02 and .06, pretty wide range. I set it to .035 like a spark plug.

Anyway, I pulled the sensor, it was clean, so I reinstalled it/reset the gap.

Sensor is working fine.
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
Still have the hard to start issue. No "check engine light" or codes.

Finally got off my butt and checked the fuel pressure.

Could be a problem - zero pressure at the rail when cranking:

20200913_164353.jpg

The fuel pump does turn on with key "ON" and key at "START".

Once engine is running, proper 31 psi at idle:

20200913_164127.jpg

Pull off the vacuum line from the fuel pressure regulator, with the engine running, fuel pressure goes up 10 psi to 41 psi, like it should:

20200913_164141.jpg


I "pinched" the return line shut, while the engine is running, the pump is putting out maximum pressure of 80 psi:

20200913_165002.jpg

Very strange, but my problem is somewhere with the fuel system.

Once the engine cranks/is running, no problems. Proper fuel pressure, regulator is working fine.
IF I get pressure at the rail when trying to start/or "key prime", starts up.
Most of the time, O pressure at rail when I go to "key prime", so hard start.
IF I get pressure at the rail on a "key prime", it does not stay, it will only go to around 20, then drop to zero fast.
While cranking, once the pressure builds up to 30-40, it fires right up.

So, no fuel at rail when trying to start, proper pressure once it is running, low to no pressure most of the time when trying to start.

Just for the hell of it, decided to change the fuel pressure regulator (FPR). This Jeep has the "two port" fuel rail, supply and return with the FPR on the rail.

Picture of FPR. Vacuum hose disconnected, rusty bolt directly above it:

20200913_165757.jpg

This bolt/bracket keeps the FPR in place:

20200913_170623.jpg

Part number on original FPR:

20200913_170652.jpg

Part number on replacement FPR:

20200913_170504.jpg

It is a PIA to pull the regulator out. Once it comes out, the two o-rings will probably still be in the rail, so you will have to pull them out.


New FPR on the left, old one on the right, with the original o-rings removed:

20200913_170327.jpg

I installed the o-rings on the FPR first, lubed the hell out of it with motor oil, was still a PIA to get it in. It might be easier to install the o-rings in the housing first, then the FPR, but I did not like that idea?

20200913_170454.jpg

I pushed the FPR in as far as it would go in, then put the bracket on, then squeezed the bracket to the back of the rail with needle nose pliers to fully seat it, then installed the retaining bolt.

No change, still zero psi at the rail after key priming.

The only other thing I can figure, fuel pump is on the way out? Maybe it has wore enough internally where it can not build up the proper pressure during the initial 3 second "key prime". I can only "key prime" three times in a row, after that, the PCM will not allow another "key prime" unless you go to "Start". Even multiple key primes will NOT build up pressure at the rail. I have to crank it over for awhile to build pressure. Once it is running, no problem.

I would say it is a problem with the "one way check valve" at the fuel pump/supply line, but there is not one, unless this external pump has a one way check valve built inside, which i doubt?

Will probably change the fuel pump out next, see what happens.

If that does not fix it, time to drop the tank. Maybe the sending unit supply side metal tube is cracked/has a hole, causing the pump not to hold pressure at the rail?

Hopefully a new pump fixes it.

That's it for now.
 

Belizeit

CJ-8 Member
CJ-8.com Member
City
River Ridge
State
La
So you have all the jeeps buttoned up ? The storm was heading to us but looks like it has now turned east, hopefully east of you some
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
So you have all the jeeps buttoned up ? The storm was heading to us but looks like it has now turned east, hopefully east of you some
My green Scrambler and JeepAddict's red Scrambler inside my garage, Gladiator blocking garage doors. My poor red Scrambler is in the yard under the Harbor Freight canopy. If the wind gets too bad I will pull the red Scrambler out of the canopy thing and park it right next to the house to be safer.

Hopefully we just get a bunch of rain for a few days, with just some stronger wind gusts. If all I have to do is pick up the yard for a few days I will be very happy.

Had to pull my skiff up the cliff some more, Tchoutacabouffa River is already pretty high. Not worried about house flooding, it sits about 50' higher then the water on a high bluff.

Hope and pray everyone else down here fairs well.

Its a shame all this rain can't make it out to California/Washington/Oregon and the other wild fire western states.
 

Belizeit

CJ-8 Member
CJ-8.com Member
City
River Ridge
State
La
Since mine is inoperable right now I built an outside barrier for my garage door early this summer. I also use my car as a barrier in front also. Usually I drive my jeep to the massive airport garage and park 3 stories up. Worked great for Katrina. Yes hoping else where fairs well.
 

HighSierra CJ

Scrambler Enthusiast
LIFETIME
CJ-8.com Member
City
Ducor
State
Ca
My green Scrambler and JeepAddict's red Scrambler inside my garage, Gladiator blocking garage doors. My poor red Scrambler is in the yard under the Harbor Freight canopy. If the wind gets too bad I will pull the red Scrambler out of the canopy thing and park it right next to the house to be safer.

Hopefully we just get a bunch of rain for a few days, with just some stronger wind gusts. If all I have to do is pick up the yard for a few days I will be very happy.

Had to pull my skiff up the cliff some more, Tchoutacabouffa River is already pretty high. Not worried about house flooding, it sits about 50' higher then the water on a high bluff.

Hope and pray everyone else down here fairs well.

Its a shame all this rain can't make it out to California/Washington/Oregon and the other wild fire western states.
I’ve really been enjoying this build thread. Especially your attention to detail while describing what you’re doing. Thank you for that! I hope everything works out OK with your weather. I’m out in California well below the creek fire. Horrible air quality, and it has sure displaced lots of people. We’d love to have some of your rain for sure. I’m not sure these fires are going to be contained without a good rain storm. Unfortunately our rain season usually doesn’t start until the end of October, to the end of November.
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
I’ve really been enjoying this build thread. Especially your attention to detail while describing what you’re doing. Thank you for that! I hope everything works out OK with your weather. I’m out in California well below the creek fire. Horrible air quality, and it has sure displaced lots of people. We’d love to have some of your rain for sure. I’m not sure these fires are going to be contained without a good rain storm. Unfortunately our rain season usually doesn’t start until the end of October, to the end of November.
Appreciate it, hope this stuff is useful/entertaining :thumbsup:

Pretty sure we dodged the storm here, barely sprinkling and maybe 25mph gusts. Those fires y'all are having are something else, hope you and yours make it through OK :cheers:
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
Swapped over fuel pumps yesterday afternoon. The top pump has been on here for 40k miles, the original supplied Hesco pump that came with the kit. I swapped on a replacement pump I purchased from Hesco awhile back, I usually keep two spares on hand.

20200914_155107.jpg
The replacement pump is slightly longer, so from a different batch/supplier perhaps.

Part number on the replacement pump. A quick Google search provides no information on this pump?

20200914_155140.jpg

Only took about 30 minutes to swap pumps, the best benefit of using an external fuel pump.

A few quick "key on/off", still not holding pressure with key ON/engine off:

20200914_161750.jpg

BUT, one major change: When the key is turned ON, the pressure jumps to 41psi, then quickly drops to zero. So, I would guess this pump is working better then the one I pulled off? It quickly hits 41psi, then drops off. So, the engine does start up now within 3 seconds of twisting the key to "Start". So, it does start easier than before.

Pressure at idle, holding steady at 30 psi like it should be:

20200914_161810.jpg

One other observation: With the old pump, the needle on the pressure gauge was fluctuating/bouncing 3-4psi. With the new pump, the needle stays rock steady.

So, did I fix it? I guess so. Starts up within 3 seconds of twisting the key to start, so no more long starting issue, so happy about that.

One thing I can't remember: With this two rail system, external aftermarket pump, FPR on the fuel rail, did the rail ever hold pressure after simply turning the key to "ON"? There is no one way check valve on the fuel supply side, so it stands to reason that without the pump running, nothing to hold pressure at the fuel rail? The fuel pump pressurizes the rail instantly, then the pump quits running without twisting the key to START, so the fuel/pressure just bleeds off down the supply side line?

On OEM Jeep 4.0 fuel systems, there is a check valve built into the pump/regulator/filter assembly. Even though I am using a Mopar MPI kit, it does NOT use an OEM fuel pump module.

On my green Scrambler, with the single line fuel rail, the pressure regulator/filter is after the pump back by the tank. So, key ON, the fuel rail will hold pressure/fuel without having to go to START. The pressure will eventually bleed off, but it takes 20-30 minutes IIRC.

Common complaint with OEM Jeep 4.0's, especially the Cherokees, is this check valve going bad resulting in long cranking times before the engine will start.

On this red Scrambler, it had always started easily, just not instantly, but no more then 3 seconds. So, maybe it has always been like this? It is kind of funny, but when I start it, I almost know when to release the key, even before it fires off. About 3 seconds crank, I presume the fuel pressure at the rail hits and holds its 41psi, it fires right off, no drama.

Will probably research some more, but I "might" put a one way check valve on the fuel supply line AFTER the pump. This will prevent the fuel from bleeding back down the supply line, allowing the rail to hold pressure.

My pump puts out 80-90 psi, BUT I have the pressure regulator on the rail. So, the check valve will hold pressure/fuel at the rail, the FPR will bleed off the excess over 40psi pressure down the return line, should not be a problem :shrug:

Something like this:

https://www.highflowfuel.com/i-2390...Q2Ylgyh-UlKN6SzJfnWXfYbf1qX2cc8hoCC18QAvD_BwE

Thoughts or opinions?

One other thought: this could all be operator error. I usually turn the key to "ON", wait for the check engine light to turn "OFF" (about 5-6 seconds), then twist the key to "START". So, pressure builds up like it should, then drops off, then I twist key to Start while pressure is dropping or at zero.

Maybe the next few starts I will just twist the key straight to Start, no pause at On waiting for the CEL to go off, like a normal car. Stands to reason this should work better since the fuel pressure gauge shows 41psi as soon as key is initially twisted to On. While the engine is cranking, the fuel pump is running continuously maintaining the correct fuel pressure.

Maybe I am the cause of my "hard starts" :crazy:
 
Last edited:

sdsupilot

CJ-8 Member
CJ-8.com Member
City
OKC
State
OK
I am confused by this. The one way valve was a common issue on some GM vehicles and would give similar symptoms, mainly long cranking until rail pressure makes the EFI happy. You could cycle the key once or twice and they typically would start right up. The thing I don't get with yours is that pressure increases, then drops to 0 until it starts while cranking.

Does your fuel pump run for the entire time you cycle the key (or at least for like 5 seconds)? Its weird that pressure goes up then drops off to 0. Since the FPR is not electric, it seems that anytime that the pump is started, pressure should build to 41 and hold. The GM TBI has a function that will turn your fuel pump off if you lose oil pressure. It also uses crank signal to turn the fuel pump on of the key was held in the "run" position long enough to turn the pump off.

The redneck way/sanity check to test this would be to unhook the fuel pump from its harness and run 12V directly to it then monitor fuel pressure. If you wire the pump directly to the battery and it holds fuel pressure and starts better, it does give a direction to look.
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
I am confused by this. The one way valve was a common issue on some GM vehicles and would give similar symptoms, mainly long cranking until rail pressure makes the EFI happy. You could cycle the key once or twice and they typically would start right up. The thing I don't get with yours is that pressure increases, then drops to 0 until it starts while cranking.

Does your fuel pump run for the entire time you cycle the key (or at least for like 5 seconds)? Its weird that pressure goes up then drops off to 0. Since the FPR is not electric, it seems that anytime that the pump is started, pressure should build to 41 and hold. The GM TBI has a function that will turn your fuel pump off if you lose oil pressure. It also uses crank signal to turn the fuel pump on of the key was held in the "run" position long enough to turn the pump off.

The redneck way/sanity check to test this would be to unhook the fuel pump from its harness and run 12V directly to it then monitor fuel pressure. If you wire the pump directly to the battery and it holds fuel pressure and starts better, it does give a direction to look.
The fuel pump is working like it should. It is wired through the Mopar MPI harness.

If you just twist the key to ON, the fuel pump will only run for three seconds, then turn off. It does this just fine. You can only key prime 3 times. After that, the pump will not get power unless/until you go to START.

Pump is powering up and running fine with key at ON/START/RUN.

There was never a one way check valve with the Mopar MPI kit, so I assume nothing to prevent the fuel pressure from bleeding back off through the supply line. The return line has the FPR on it to bleed off the excess pressure when the pump is running. So, pump runs three seconds, hits 41psi, then the time expires and pump quits running, so nothing prevents the fuel/pressure to bleed back down the supply line. I guess?

As long as the pump is running, the FPR maintains the correct pressure at the rail. Once the pump cuts off, nothing to hold the fuel/pressure in place at the rail, so it instantly bleeds off to zero.

The pump powers on with the key at ON (3 seconds), Start, and then back at run. The circuit is working properly.

If I just quickly twist the key from Off to Start to Run it probably will work fine, even without a check valve?

It starts easily again, within 3 seconds of cranking. I started it up about 20 times yesterday. It quickly starts within 3 seconds of cranking.

I just maybe am over thinking it/creating an issue where none exists?

I do like the idea of the check valve on the supply side to keep the rail pressure from bleeding off when the pump quits running.

I will probably try your idea of jumping the pump off the battery to maintain pressure before it starts to see what it does :thumbsup:
 

Belizeit

CJ-8 Member
CJ-8.com Member
City
River Ridge
State
La
My wife had the 96 Cherokee with 4.0 HO for 22 years. Pump in the tank. Never had a problem with the pump. She never just turned on the key and waited a few seconds then cranked it over. She would turn the key on and crank 2-3 seconds and it would start.
 

sdsupilot

CJ-8 Member
CJ-8.com Member
City
OKC
State
OK
That makes sense. I bet it will be fine either with a check valve or just starting to crank within a second of turning the key to run. Hope all is well in your area. It looks like the rain should be pushing past now.
 

Randyzzz

Blown Budget
LIFETIME
CJ-8.com Member
SOA Member
City
Redmond
State
OR
Swapped over fuel pumps yesterday afternoon. The top pump has been on here for 40k miles, the original supplied Hesco pump that came with the kit. I swapped on a replacement pump I purchased from Hesco awhile back, I usually keep two spares on hand.

View attachment 87047
The replacement pump is slightly longer, so from a different batch/supplier perhaps.

Part number on the replacement pump. A quick Google search provides no information on this pump?

View attachment 87048

Only took about 30 minutes to swap pumps, the best benefit of using an external fuel pump.

A few quick "key on/off", still not holding pressure with key ON/engine off:

View attachment 87049

BUT, one major change: When the key is turned ON, the pressure jumps to 41psi, then quickly drops to zero. So, I would guess this pump is working better then the one I pulled off? It quickly hits 41psi, then drops off. So, the engine does start up now within 3 seconds of twisting the key to "Start". So, it does start easier than before.

Pressure at idle, holding steady at 30 psi like it should be:

View attachment 87050

One other observation: With the old pump, the needle on the pressure gauge was fluctuating/bouncing 3-4psi. With the new pump, the needle stays rock steady.

So, did I fix it? I guess so. Starts up within 3 seconds of twisting the key to start, so no more long starting issue, so happy about that.

One thing I can't remember: With this two rail system, external aftermarket pump, FPR on the fuel rail, did the rail ever hold pressure after simply turning the key to "ON"? There is no one way check valve on the fuel supply side, so it stands to reason that without the pump running, nothing to hold pressure at the fuel rail? The fuel pump pressurizes the rail instantly, then the pump quits running without twisting the key to START, so the fuel/pressure just bleeds off down the supply side line?

On OEM Jeep 4.0 fuel systems, there is a check valve built into the pump/regulator/filter assembly. Even though I am using a Mopar MPI kit, it does NOT use an OEM fuel pump module.

On my green Scrambler, with the single line fuel rail, the pressure regulator/filter is after the pump back by the tank. So, key ON, the fuel rail will hold pressure/fuel without having to go to START. The pressure will eventually bleed off, but it takes 20-30 minutes IIRC.

Common complaint with OEM Jeep 4.0's, especially the Cherokees, is this check valve going bad resulting in long cranking times before the engine will start.

On this red Scrambler, it had always started easily, just not instantly, but no more then 3 seconds. So, maybe it has always been like this? It is kind of funny, but when I start it, I almost know when to release the key, even before it fires off. About 3 seconds crank, I presume the fuel pressure at the rail hits and holds its 41psi, it fires right off, no drama.

Will probably research some more, but I "might" put a one way check valve on the fuel supply line AFTER the pump. This will prevent the fuel from bleeding back down the supply line, allowing the rail to hold pressure.

My pump puts out 80-90 psi, BUT I have the pressure regulator on the rail. So, the check valve will hold pressure/fuel at the rail, the FPR will bleed off the excess over 40psi pressure down the return line, should not be a problem :shrug:

Something like this:

https://www.highflowfuel.com/i-2390...Q2Ylgyh-UlKN6SzJfnWXfYbf1qX2cc8hoCC18QAvD_BwE

Thoughts or opinions?

One other thought: this could all be operator error. I usually turn the key to "ON", wait for the check engine light to turn "OFF" (about 5-6 seconds), then twist the key to "START". So, pressure builds up like it should, then drops off, then I twist key to Start while pressure is dropping or at zero.

Maybe the next few starts I will just twist the key straight to Start, no pause at On waiting for the CEL to go off, like a normal car. Stands to reason this should work better since the fuel pressure gauge shows 41psi as soon as key is initially twisted to On. While the engine is cranking, the fuel pump is running continuously maintaining the correct fuel pressure.

Maybe I am the cause of my "hard starts" :crazy:
Wish I had seen that valve years ago- I bought one from Ford- it was close to $100...and it’s still sitting in my tool box. One of these-
C6F4FBF9-CBF4-49A1-AC6D-8BB986D6A997.png
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
Luckily for me, and most of the rest of Mississippi, we dodged the bullet this time, with regards to the hurricane.

Light rain and maybe 30mph wind gusts at my house, so no problems.

My pier went underwater, but that happens anytime the river runs high:

20200915_085058.jpg

Red Scrambler/Harbor Freight garage survived:

20200916_090122.jpg

Used the Scrambler a bunch the last few days to haul around my "paint booth" to haul off yard debris:

20200916_160404.jpg

Saw a bunch of these guys, but they would not help me do yard work:

20200915_100303.jpg

So, still having my "does not start on first key turn" issues. As long as I get/hold 41 psi at the rail when I go to start, it fires right off. I will typically "key prime" once, then start on 2nd attempt, fires right off.

It just seems really strange that this just started happening?

I could add a one way check valve in the supply line to prevent fuel/pressure from bleeding back down past the pump, if that is the problem, but I have never had this problem before, without a check valve? I do not know/think the OEM Jeep CJ sending unit has any type of check valve on the supply side connection?

Maybe an injector(s) leaking? But, this thing bleeds down INSTANTLY from 41psi to zero, like 3 seconds. That would be a hell of an injector leak!! And, I am not blowing out black smoke when it starts like the engine has a bunch of unburned fuel in the cylinders? No performance/MPG issues, either?

It is just really strange how fast the pressure drops to zero, without any visible/odorous fuel leaks? I am pretty sure it is not leaking gas, 30-40psi while running would drain the tank pretty fast/noticeable?

Maybe my 10 year old rubber fuel supply line, that runs on top the tank from the sending unit to the fuel filter, has a small tear that allows air in/pressure to drop, but not big enough for fuel to leak out of?

I might lower the tank down enough to change out the rubber supply line first, maybe there is an issue there?

But, adding a $30 check valve would be much easier :smokin:

The check valve would be a "band aid" covering up another issue :twocents:

Like I said earlier, this issue just popped up two months ago at Sand Blast in Michigan, so something changed. Maybe the OEM sending unit got damaged somehow, tube loosened at the top of sending unit, vertical pick up tube split, allowing a pressure loss? The issue is present with a low or full tank.

Will probably have to drop the damn tank to figure this out :banghead:
 
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