Re L29 454 7.4 fuel fill low pressure!! Help!!
#1
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So I wasn’t able to get over 3500 RPM so when I came back in I tested the fuel pressure after I diagnosed everything else and I’m coming up with 29/30 pounds at idle and 35 at key on.
I removed the fuel, cool system, checked everything replaced the fuel pressure regulator, because the one I had was rusted out at the vacuum connection. replace the fuel pump check the wiring and then I put everything back and I’m getting the same. I also replace the filter on the fuel water separator. Hold pressure pretty well, so I’m not worried about the injectors leaking and I just had them all flow tested.
There was an intermittent issue at the relay, but I fix that.
Any help would be appreciated I’m buying beers.
Also, if anyone has a scan tool for this military, they’re willing to lend me or live in San Diego. Let me know.
I removed the fuel, cool system, checked everything replaced the fuel pressure regulator, because the one I had was rusted out at the vacuum connection. replace the fuel pump check the wiring and then I put everything back and I’m getting the same. I also replace the filter on the fuel water separator. Hold pressure pretty well, so I’m not worried about the injectors leaking and I just had them all flow tested.
There was an intermittent issue at the relay, but I fix that.
Any help would be appreciated I’m buying beers.
Also, if anyone has a scan tool for this military, they’re willing to lend me or live in San Diego. Let me know.
#2
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Your injectors all passed and held pressure well? Ive almost given up on flowing/cleaning the l29 injectors and just started stocking new quality replacements because I almost NEVER see 8 of them even after cleaning, testing, etc that dont have a couple that dont leak or flow erratically. Have you tested the fuel pressure on the water, at wot under full load when it doesnt get past 3500?
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Bravo454 (09-03-2023)
#3
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Your injectors all passed and held pressure well? Ive almost given up on flowing/cleaning the l29 injectors and just started stocking new quality replacements because I almost NEVER see 8 of them even after cleaning, testing, etc that dont have a couple that dont leak or flow erratically. Have you tested the fuel pressure on the water, at wot under full load when it doesnt get past 3500?
I’m getting 30 pounds right after the pump and I tested that by hooking up a fuel line to the outlet of the fuel pump and connecting the pressure gauge directly to that line bypassing the rail and got the same pressure.
It’s struggling to get fuel so my next step is to take that siphon out of the fuel tank and make sure that’s clean, but I have to put some PB blaster on there let it soak for a while and then blowback the line from the fuel water separator.
I removed all the fuel lines and blew them all out. They seem fine, and I replaced the fuel water separator filter.
I almost feel like pulling out the whole fuel system and mounting a fuel filter, adjustable, regulator, and fuel pump right on the firewall there.
Yes, I also check for air leaks, and once I bled off the original key from the gauge, there was no more air bubbles if I bled more fuel off.
#4
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what I’m hoping is there is something in between the fuel tank and the fuel water separator that I’m missing hopefully once I check that out and I can eliminate it but it’s just extremely frustrating.
The motor has two hours on it. I just put back the original equipment for the fuel system since the owner said he replaced the pump once I took it off I replaced the pump again and a fuel pressure regulator but again Still same issue.
The motor has two hours on it. I just put back the original equipment for the fuel system since the owner said he replaced the pump once I took it off I replaced the pump again and a fuel pressure regulator but again Still same issue.
#5
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Did it ever run right ? or did you buy it without a water test, is the fuel vent to the tank clear, have you tried taking off the fuel fill cap and retest fuel pressure.
The following 2 users liked this post by F-2 Speedy:
articfriends (09-03-2023), Bravo454 (09-03-2023)
#6
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I did not take off the fuel cap or test to see if the vent is clear. Great ideas… I’m also thinking that the low pressure fuel lines from the fuel water separator to the pump and regulator should be replaced but I can’t find anybody that makes them and I’m not spending $500 a line. If anybody knows someone that makes fuel lines, let me know.
I replaced almost everything in the complete and all the surrounding parts.
One thing I did notice is that when I went from 1000 RPMs to 2000 RPMs, the fuel pressure dropped I don’t know if that means anything or not but I think it’s starving for fuel.
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articfriends (09-03-2023)
#7
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#8
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i wish they just had the pump etc on the firewall.
#9
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Hook up a remote tank to bypass tank and lines.
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Bravo454 (09-03-2023)
#10