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Fuel pressure issue


2trux

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Lately I have been having issues with slight missing while on the highway. Yesterday after stopping for the light on the off ramp the idle became very rough and the engine died. It restarted after about 30 sec. At the next stop it died again. When I got home I put the fuel pressure tester on. When I turn the key the pressure jumps to 30 psi. After starting the pressure drops to 20 psi and the idle gets rough and the engine soon dies.
Does this sound like it could just be a clogged filter, or would you think it's the fuel pump, or possibly the regulator. I ordered a filter and new pump but would prefer to not install the pump if not needed.

Thanks
 


enjr44

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Well, I guess my first thought is, "Who knows!" I'd install the filter and see what happens.
 

2trux

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Well I drove it again before replacing the filter and the fuel pressure was 36psi. I have replaced the filter and have not had any other problems yet, I'll see what happens when I head home from work today. This seems to be when it normally has problems.
 

2trux

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Well it doesn't look like the filter solved the problem. The problem seems to appear after driving it than shutting down and restarting after a short time. The fuel pressure at idle was dropping below 20 psi then the engine would die. What was interesting was as long as I was driving it seemed to run OK but when I got to a light the engine would stumble and die. When the light turned green I would restart and it would get me to the next light.
This morning it ran perfect as I came to work.
I don't know if this is related but often I have high engine speeds when I expect idle. Example: as I am approaching a red light I put it in neutral to coast up to the light and the RPM stays at 1800 until I stop then it drops back to a normal idle.
I will replace the pump this weekend and see if anything changes.
 

dave2575

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I have an 88 XLT with dual tanks and mine did the same thing a while ago. I started (just like you are) by doing the easy/cheap things first. Make sure you have enough gas, if you can start it.. let it get warm and then inspect your system for leaks then turn it off. Make sure you have a good seal on the gas cap. Then it doesn't hurt to check for any codes, pull the vacuum hose off the regulator and smell/look for gas, replace regulator if gas is present in the hose, replace Filters, could be 1 to 4 filters depending on your fuel system(my dual tank came with 4 filters). And then you get into the not so easy/cheap things. Do the inline HP pump first, then do the in-tank pump/filter assembly. My truck had a bad in-tank pump/filter assy.. NO FUN! I hope thats not the case for you. good luck
 

2trux

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I pulled the bed and replaced the pump last weekend. This was actually easier than I thought it would be. (It also gave me a chance to pressure wash the mud off the top of my frame.)
I had previously replaced the filter (under the cab) which didn't help.
After the pump replacement I haven't had any problems so it may have resolved the issue. I have checked the regulator before and there was no gas, I will check it again as I sometimes get high idle issues.
From what I can see there is only 1 external filter and only the in-tank pump. The running pressure went from 36 up to 40 psi at idle with the new pump.
 

dave2575

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Sounds like you got it. Congrats :beer:
 

enjr44

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I could be wrong (very likely, LOL); but, the high rpms when coasting sounds normal. I think it is a computer software thing....
 

dave2575

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I know mine has always idled high. When I start it in the morning the rpm's will stay at 1.5K untill it warms up then it will drop to around 1K, and It wont drop down to its normal 800 rpm idle tell its in gear. It s a good thing I have dual tanks lol
 

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