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Retitled: 83 Scrambler resto-mod finally gaining momentum

Have you check the injectors, if I remember someone else had a problem similar to yours where it was the injectors being bad.
 
I think I've isolated the issue further...

dropped a little fuel into the throttle body.. fired right up (and quit.. I wasn't dripping it in)...

rented a set of "Noid" lights, which test the signal going to your injectors.. I plugged it in to two different injector harnesses with positive (flashing light) results while cranking

rented a fuel pressure tester and tested pressure at the rail.. my vacuum line to the fuel regulator is unplugged so I should get 39 psi at the pressure port on the fuel rail.. I got 12 on the gauge.

fuel pump is new
fuel filters are new
fuel lines (rubber parts) are new
fuel rail and injectors all came off the (running) motor before I rebuilt it, and I replaced all the o-rings on the injectors
I'm showing no leaks anywhere..

as I'm waiting for replacement filler/vent hoses (which is another long story, after sending me the wrong part, and the correct part to Keith/kctango, I've reordered the correct part numbers from Morris4x4, which they NOW show are back ordered.. banghead)

would having the fuel filler hoses unplugged (no filler neck, no cap) reduce pressure forward of the fuel pump, enough to drop the pressure from 39 lbs to 12 lbs?
 
I reinstalled the filler/vent hoses, filler neck, and gas cap...

I hooked the fuel pressure test kit back up, primed (several times) the fuel pump and.. no change: 12 lbs at the rail.

I bled the test kit and noticed a lot of air coming with the fuel down the kit drain tube. I then re-tested and after about a dozen primes and attempted starts, got the pressure up to about 15lbs.

At this point, I thought I might have a bunch of air in the lines preventing me from getting pressure, so I continued the purge/prime technique but never saw it go above 12 lbs again... ended up quitting at about 1130PM as I didn't want to p-ss off the neighbors to much with motor cranks..

I'm going to try the purge/pressurize bit again in the morning to see if I can bump up the pressure that way..
 
At least you got it fired and have it narrowed down! :thumbsup:

I think something is wrong somewhere. The filler neck/vent has nothing to do with this as you could be running the pump line out of a jerry can, pop bottle, open bowl, etc and still see proper pressure as long as the intake line is in the gas. The neck/vent are just open to atmosphere? You wouldn't want the tank totally sealed up airtight.

That's a huge pressure difference, like carb pressure vs. EFI pressure.

The simple questions:

Did you verify a full 12V at the fuel pump?

No kinks in the fuel lines?

You're sure it's an EFI pump and not for a carb setup? Could even be a case of the wrong part in the right box? I don't know if they make carb pumps in that same form factor, but the pressure sounds like it's for a carb.

If your pressure regulator/filter deal was bad and the pump was good, the regulator would have to be putting a huge amount of gas back through the return line, I would think. Can you run the return line into an empty gas can to check?

Any way to get a pressure guage between the pump and filter?

Remove/bypass the prefilter, maybe it's clogged/bad?

I would think a leak somewhere on the pressure side of the pump would spit fuel, not pull air. Maybe check the lines from the pump to the tank?

Maybe run a new line from the pump inlet into a full gas can to eliminate a leak sucking in air between the pump and tank?


Those are my thoughts. I don't think there's any way an EFI pump in a working setup needs primed/purged more than turning it over for a few cranks (and shouldn't require any additional equipment like your pressure tester). I didn't prime mine at all and don't remember ever reading about the need to do so.
 
If the pump is only putting out 15lbs, sounds like a TBI pump:shrug: You need, IIRC, close to +40lbs for the MPI:shrug:

On my red Scrambler, it took about 10 minutes to bleed out the fuel rail and all the lines. Everything on mine was new, so it was all empty. On mine, due to the Hesco computer, I could only "prime" it 3 times in a row with the key, then would have to wait a minute before trying to bleed/prime the pump with the key, some kind of relay safety issue. Once mine started spitting gas, I still re-primed it about 5 times to make sure all the air was out.

BigWalton might be on to something, check the voltage at the pump. Maybe you have a bad relay:shrug:
 
Interesting, my lines were all drained from where I ran new soft lines and I didn't prime at all. Filing your experience away for future reference (yeah, like my memory is worth a damn! ;))
 
Pump is an airtex E2000, which I understand to push well over the required pressure, although a quick search on my phone is not revealing specs. I'll check the voltage but it does the 1-2 second prime just like it should.

While I was priming last night I ran into the same safety catch as Raymond, 3-4 primes and then I had to crank it, or wait.

I have a pre-filter, pump, and filter all in line on rear cross member. No leaks observed. I'm using 5/16 supply line, combination of rubber and factory CJ metal lines.

I keep coming back to wonder if I have a PCM issue between priming, starting, and running. CPS related?
 
bigwalton said:
At least you got it fired and have it narrowed down! :thumbsup:

I think something is wrong somewhere. The filler neck/vent has nothing to do with this as you could be running the pump line out of a jerry can, pop bottle, open bowl, etc and still see proper pressure as long as the intake line is in the gas.
Click to expand...

I've only got 3-4 gallons in the fuel tank.. may put some more in just to make sure the fuel pickup isn't sitting half in gas.. my 22 gal tank may be only a 17-18 in practice if I've got a problem there..
 
When I was trying to get my 91 4.0 YJ started , I pulled the relay and put a jumper across to run pump till I had fuel to the rail
I had my pressure gauge on with the bleeder depressed and dumping into a pan
Does that make sense ?
 
If you are running a filter after the pump, I wonder if that is causing an issue?

I only run a "pre" pump filter, no problems. Maybe temporarily pull your "post" pump filter and see if it starts:shrug::twocents:

The E2000 "should" have enough pressure/flow. How did you adapt it's "quick connect" ends to your CJ fuel rail?
 
jims chop shop said:
When I was trying to get my 91 4.0 YJ started , I pulled the relay and put a jumper across to run pump till I had fuel to the rail
I had my pressure gauge on with the bleeder depressed and dumping into a pan
Does that make sense ?
Click to expand...

That's a great idea :thumbsup::cheers:
 
jims chop shop said:
When I was trying to get my 91 4.0 YJ started , I pulled the relay and put a jumper across to run pump till I had fuel to the rail
I had my pressure gauge on with the bleeder depressed and dumping into a pan
Does that make sense ?
Click to expand...

just verified that I"m getting 12V at pump.

makes sense.. how long/how much did you have to pump? I'm well past the point that I think I should have air in lines.. but certainly possible
 
I have solved the fuel pressure issue, and I'm a little proud of my logic and embarassed of my ignorance..

I was afraid the air in the fuel lines was coming from the intake in the tank, as I saw no fuel drips where leaks may be.

I crimped the fuel return line to see if I could build pressure (pump is rated to 90psi) by closing the "loop" of the fuel return line: no difference.

I put another 2 gallons of gas in it... bingo. 38psi at the rail. I think my fuel pickup was sucking in air along with fuel. I was "out of gas".

The fuel pressure gauge now climbs to 38, jumps temporarily above it and then re-settles at 38 (which I take to indicate that the fuel pressure regulator is functioning).

and now.. it's still not starting.. still get the "want to sound" where it sounds like it wants to turn faster and get hints of combustion, but don't take off.. letting the battery charge under a jump right now to give it a few minutes and will then try again..
 
Back to basics... thinking through why I may not getting a start.

battery is good
fuel and fuel pressure are good
signal to the fuel injectors has been verified by noid light/tester
I just did a dry quckie compression test (on a cold and newly rebuilt motor) and got 110lbs quickly built on #2 cylinder
I've verified that I'm getting spark at a spark plug
I've verified (I think) that my TDC and timing are set at 0: air pressure at #1 spark plug hole, timing mark at 0, rotor at 1, and piston at the top of its travel.. this is one area I'll definitely check and re-check again...

I pulled three of the (brand new) spark plugs.. one appeared to be covered in sort of a wet/black soot, the next two appeared to be bone dry (shortly after multiple attempts to start the engine).. no wetness, no gas smell, could be a sign that only that one plug is getting fuel?

- when I was purging the fuel pressure gauge, I did get some dark fuel out of it (all the fuel is fresh, so it must have been cleaning the bottom of the (previously cleaned out) fuel tank and the rust/dust out of the fuel lines which have sat dry for over a year mounted in place

things that I'm thinking may be the culprit:
- timing: as stated, I'll re-check
- actual injectors: these are the original injectors from before I rebuilt the engine, which ran fine before I rebuilt it.. unless the initial purge of rust/dirt from the dry fuel lines clogged up all 6 of them, I'm not sure how they could all be bad.. that said, I'm surprised after all the start attempts that i've got dry plugs coming out of the cylinders..
- a ground somewhere in the system.. maybe something to do with NSS or park sensor. I've grounded what I think may need it, but not sure if I've overlooked one, or perhaps did one wrong. If I did miss a ground, would it still allow me signal to the injectors and start signal to the starter? I'm thinking those would be interrupted?

I like to learn, but this is getting to be a PITA. :banghead:
 
NSS issue would keep it from doing anything.

Does yours have an idle air controller on the throttle body? Mine went bad last summer and I couldn't get the Jeep to start. I happened to put my hand on the thing while trying to figure out what was wrong (took all morning :banghead:) and I realized it was hot. Unplugged it and the Jeep started right up, just idled horribly. Replaced it and all was good.
 
You said it started before with some gas poured in the throttle body
Did you try that again ?
 
bigwalton said:
NSS issue would keep it from doing anything.

Does yours have an idle air controller on the throttle body? Mine went bad last summer and I couldn't get the Jeep to start. I happened to put my hand on the thing while trying to figure out what was wrong (took all morning :banghead:) and I realized it was hot. Unplugged it and the Jeep started right up, just idled horribly. Replaced it and all was good.
Click to expand...

I distinctly remember that episode :thumbsup:
 
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