lift pump issues
11-06-2005, 11:17 AM
#1
Registered User
Thread Starter
lift pump issues
Yesterday during a 90 mile trip, my fuel press dropped from a normal of 25 @ 65 mph, to as low as 14. I got where I was going, and checked the prefilter (suspected possibly a bad batch of fuel). It was clean as a whistle.
Got back home, and pressurized the fuel system with 10 psi shop air, and checked for leaks. Couldn't feel any anywhere. So, I took some water & dish soap and made a soapy mixture, which I then sprayed on everything to see if I got any bubbles from a small leak. NADA.
So I put the new lift pump on, and dissected the old one. Ain't much to them there suckas that's for sure. Didn't really see anything for sure wrong.
While I was under there, I noticed the boot for my fuel solenoid was bad, and the heim joint at the end of the solenoid linkage was stuck, and the cotter pin was gone, so that the solenoid could come off the lever. Took that off and repaired/rebuilt it, and made a new boot out of some old inner tube material.
Started it up, and FP was back up to 30 psi @ idle (OFV is shimmed). Removed the shim from the OFV, and now FP is 24 psi @ idle.
Took the truck for a test drive, seems to be doing good. Consistent 20-24 psi FP during most driving, and only drops below 20 psi momentarily during hard acceleration, then climbs back up.
Have to see how she does on the highway today.
BTW...it IS possible to replace the lift pump without removing anything else, but it is a PITA and your arms will hate you the next day.
And whose bright idea was it to sandwich the prefilter/heater housing between the lift pump and the block ???? Getting gaskets in there was a PITA and cost me an hour of time. Good thing I had extra small block chrysler gasser fuel pump gaskets (same gasket BTW), as the new lift pump only came with one gasket, and you need two for this job. I put the prefilter/heater assembly on using the bolts and some washers to let the gasket stuff (light film) set before I removed the bolts to put the lift pump on. That was when I found & fixed the fuel solenoid. I also used a longer bolt from the bolt bin to pull the lift pump on (compress the pump part) until I could get the correct bolts in.
And priming the truck is a bunch easier when you pressurize the tank with 10 psi...you just crack a fitting on top of the fuel strainer, and VOILA !...it's primed and she starts right away.
The bad part, is I will have to do some of this again this week, as I had planned on replacing ALL of the fuel lines, but had yet to buy the line....so now, I get to do that as a seperate job, instead of all in one shot.
Got back home, and pressurized the fuel system with 10 psi shop air, and checked for leaks. Couldn't feel any anywhere. So, I took some water & dish soap and made a soapy mixture, which I then sprayed on everything to see if I got any bubbles from a small leak. NADA.
So I put the new lift pump on, and dissected the old one. Ain't much to them there suckas that's for sure. Didn't really see anything for sure wrong.
While I was under there, I noticed the boot for my fuel solenoid was bad, and the heim joint at the end of the solenoid linkage was stuck, and the cotter pin was gone, so that the solenoid could come off the lever. Took that off and repaired/rebuilt it, and made a new boot out of some old inner tube material.
Started it up, and FP was back up to 30 psi @ idle (OFV is shimmed). Removed the shim from the OFV, and now FP is 24 psi @ idle.
Took the truck for a test drive, seems to be doing good. Consistent 20-24 psi FP during most driving, and only drops below 20 psi momentarily during hard acceleration, then climbs back up.
Have to see how she does on the highway today.
BTW...it IS possible to replace the lift pump without removing anything else, but it is a PITA and your arms will hate you the next day.
And whose bright idea was it to sandwich the prefilter/heater housing between the lift pump and the block ???? Getting gaskets in there was a PITA and cost me an hour of time. Good thing I had extra small block chrysler gasser fuel pump gaskets (same gasket BTW), as the new lift pump only came with one gasket, and you need two for this job. I put the prefilter/heater assembly on using the bolts and some washers to let the gasket stuff (light film) set before I removed the bolts to put the lift pump on. That was when I found & fixed the fuel solenoid. I also used a longer bolt from the bolt bin to pull the lift pump on (compress the pump part) until I could get the correct bolts in.
And priming the truck is a bunch easier when you pressurize the tank with 10 psi...you just crack a fitting on top of the fuel strainer, and VOILA !...it's primed and she starts right away.
The bad part, is I will have to do some of this again this week, as I had planned on replacing ALL of the fuel lines, but had yet to buy the line....so now, I get to do that as a seperate job, instead of all in one shot.
11-06-2005, 07:34 PM
#3
Registered User
Thread Starter
Well, generally, it's not needed like a boost gage or pyro, but it is dang nice to have when troubleshooting.....which is the main reason why I installed it.
And it is one of them things, that if ya have it, it is nice to see what's going on.
And it is one of them things, that if ya have it, it is nice to see what's going on.
07-29-2019, 11:07 AM
#5
Registered User
Something to keep in mind while troubleshooting. The section of fuel line between the tank and the lift pump is normally under vacuum, the pump sucks fuel from the tank. Pressurizing the line has a slim chance of reviling a leak under those circumstances. The best way is to isolate both ends of the line and put it under a vacuum and watch how fast it bleeds down. Also, if the tank vent system isn't working correctly it can hold enough of a vacuum to overcome the lift pump.
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