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MPI New fuel pump problem

HighSierra CJ

Scrambler Enthusiast
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Ducor
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I am Running a Mopar fuel injection kit on my Scrambler. I, like many others bought my kit from Hesco. I recently decided to replace my fuel pump, not because it was bad, but because it is 15 years old (preventive maintenance). I ordered a new pump from Hesco and installed it. Benny (from Hesco) told me that because the original pump was discontinued, they now sell a different brand pump. The new pump arrived with no brand name, or information at all. the new pump functions fine, and the jeep drives fine, BUT the pump is VERY VERY loud. At an idle the pump sounds normal. once you accelerate, the pump gets a lot louder, and stays loud even at an idle. It is loud enough that I can hear it at 55MPH with the top off. Maybe I got a bad one??
Has anyone else had this experience with the replacement fuel pumps? Also, does anyone have a recommendation on a high quality brand fuel pump that will work with the MPI setup?
Thanks in advance!
Mike
 
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spankrjs

Scrambler Junkie
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Biloxi
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MS
I was scared this would eventually happen :(

The original kit supplied pumps had some markings, but I could never get them to cross over to any manufacturer. My experience with other brand external pumps (Airtex, Carter, etc) has been less then stellar. Most are loud, and when I owned/drove my old tan GM TBI injected 350 powered Scrambler, a pump would only last maybe a year/8-9,000 miles. (Current owners haven't had pump problem yet as far as I know!!!!!!)

I swapped out my original kit supplied external pump on my red Scrambler on it's first trip out to Moab. False diagnosis on my part. I put on a new/spare/original Hesco external pump and have close to 60k miles on it, no issues. If I was you, and the old pump was still working fine, I would swap it back on and keep the "replacement" as a spare :twocents:

On my green Scrambler, which also has a Mopar MPI kit, I installed a "TanksInc" retrofit "internal" fuel pump inside the OEM 15 gallon steel tank. Details start around post #287:


It uses a supposedly good quality Walbro fuel pump. I have only had this set up installed a few years/couple thousand miles/only one long 8 hour trip of about 600 miles total, but so far no problems.

I will probably install something similar inside my red Scrambler's OEM 20 gallon tank in the future.

The issue with the internal pumps: if/when they fail, you are stuck. So, on my green Scrambler, I installed a new Hesco external pump plumbed through the OEM sending unit. If the internal pump fails, I only need to swap over one rubber fuel line, disconnect/connect one electric plug from one pump to the other, back on the road in about 10 minutes.

IF I eventually go to an internal fuel pump in my red Scrambler, I will leave an external pump in place, just in case. Took a few hours in the garage to get it all mounted up and plumbed, but it will save my butt on the road if I ever need it :twocents:

Long winded, but that's my thoughts :cheers:
 

HighSierra CJ

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Your thoughts are very appreciated, and respected👍. Thanks for taking the time to help me with this. I was leaning towards an in tank conversion. I’ll check your thread out. Thanks again,
Mike
 

CJ7Pilot

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I picked up an MPI 258 for my black Scrambler, which I'm hoping to install later this year.

I'm planning to try this Novak in-tank setup: https://www.novak-adapt.com/catalog/fuel-system/cj-fuel-module/

It's expensive, but I happen to have one on hand, because the previous owner of my black Scrambler picked it up for an engine swap.

It puts out a little more pressure than needed, but I'm hoping the pressure regulator on my MPI fuel rail can handle it.
 

spankrjs

Scrambler Junkie
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Biloxi
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MS
I picked up an MPI 258 for my black Scrambler, which I'm hoping to install later this year.

I'm planning to try this Novak in-tank setup: https://www.novak-adapt.com/catalog/fuel-system/cj-fuel-module/

It's expensive, but I happen to have one on hand, because the previous owner of my black Scrambler picked it up for an engine swap.

It puts out a little more pressure than needed, but I'm hoping the pressure regulator on my MPI fuel rail can handle it.
You should be fine on that pump, your regulator should be able to cut it down to the 31psi idle pressure. I am pretty confident the original Hesco pumps put out way more then 31psi :thumbsup:

I would maybe install a new pressure regulator, with both o-rings, and maybe injector o-rings, if the parts you have are older/used.
 

sdsupilot

CJ-8 Member
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City
OKC
State
OK
I used the tanks inc retrofit on my 8 as well for the TBI swap. I really can't hear the fuel pump even with the engine off. It was a fair amount of work, but I am really happy with it. I didn't run a backup fuel pump as @spankrjs mentioned above. My luck with internal fuel pumps is about 35 years of my current 5,000 miles per year. If it dies on the trail I will be very sad though...
 

CJ7Pilot

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Yuba City
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I copied this from another forum, maybe it could be a work around for a fuel injection pump as well 😉 :

I was in the desert in a 4x4, hunting mule deer. The fuel pump quit working. I drained the windshield washer tank and filled it with gas, then adjusted the hose to spray down the carb instead of on the windshield. Every pump of the waster lever would roll me along a few dozen feet. This worked, but I wanted a better constant source while using the washer motor to accelerate. So I got a beer bottle and punched 3 holes in the cap with a nail and drank the beer. Then I filled the bottle with gas through the holes. Not easy and probably not necessary if I wanted to just reattach the cap with some pliers, but that's what I did. I then inverted the beer bottle into one of the carb barrels and fired up. 3 holes was a little over 1,000rpm. A fourth hole though, got me 1250rpm and what I was looking for. I could shift and not over rev, crawl without stalling on flat ground. I could hit the washer spray knob and accelerate. This got me maybe 40 miles back to a highway. Since I was on the highway, why not keep going. Ended up in Carson City, NV where I could pull into an auto parts store and buy a replacement pump.
 
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HighSierra CJ

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Thanks guys for all of the thoughts and experiences. I just ordered the in tank pump from Novak. Seems like the most plug and play option.
I’ll keep you posted on the results.
Mile
 

CJ-8_Jim

Scrambler Junkie
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NW Chicago Suburb
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IL
E2000 fuel pump works fine on my Hesco MPI system. It's a frame-mounted pump used on 1980s Econolines.
(It's a plug-n-play installation)
 
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tmancj7

Basic User
City
Denver
State
CO
I went with the Novak in-tank pump setup for my Hesco MPI conversion, have been running it a few years with no problems. The fuel sender arm is NOT correctly calibrated, mine reads 1/4 tank low all the time. Not a deal breaker but it is one of those annoying things I need to go back and fix.
 

bigwalton

Alaskan Postal nutjob
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Dexter
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MI
I've learned that these pumps are very sensitive to restrictions on the intake side. The postal has had three different pumps over time and they've all been really quiet. When I put the FAST kit on the 360 (at the time) in the 77 Cherokee, it was screaming loud and I dropped the tank to find a piece of RTV (that the shop overused when they installed the dual-tank setup) was clogging the pickup, which had no filter sock. As soon as I reworked the fuel setup, it quieted waaaay down, but it's still a lot more noticeable than the postal's.

I want to go to an internal pump but the only way I'll do it is if I add an access door in the bed floor. I've seen them done a number of times and as soon as I saw it, I knew that's what I wanted to do. Solves the pump swapping issue as well as making it easy if there's every any fuel line or sender problems.
 

Ron84cj

Scrambler Junkie
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City
West Bend
State
WI
It also makes a difference if your fuel filter is before or after the pump. I learned that the hard way. The filter needs to be AFTER the pump. As soon as I made the switch the pump got super quiet. I've been using a Walbro 255 for the last 5 years.
 

cj8jeff

Basic User
City
Glendora
State
CA
I too have the Mopar MPI kit. The original fuel pump lasted for quite a few years till it failed. The multiple replacements did not last long. Went w the Novak in tank and no more issues since. Same issue w guage calibration off and idea for an access door to replace in future. Scrambled minds think alike
 
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