ok, gents. here is a puzzler, at least for me. having fuel presure problems with my SPF P2116. Roush 427, Edelbrock 1725 fuel pump supposed to be 6-7 lbs. when i shut eng. off and look down carb. throat see fuel leaking down carb throat. took it to my mechanic who runs Calif. smog check station and found out i have 10 lbs. fuel pressure at the carb. so i put in pressure regulator and gauge. set regulator at 5 lbs, gauge say the same 5 lbs. and it ran fine. shut eng. off and gauge still read 5 lbs. about an hour later checked again and it was down to 2 lbs. i'm thinking that when eng is shut off there should be no more fuel pressure, right? so i'm thinking change fuel pump to a stock Ford product or is 5 lbs. pressure ok in line after eng. is shut off? any help would be appreciated. planned on driving GT to Willow Springs this a.m. but car would not start. BIG disappointment.
fuel pressure
- Thread starter john bach
- Start date
If you have found that the fuel pump is working properly, and the pressure regulator is also working, then the next step is really easy. Try this before you start buying parts. Pull the bowl off your primaries and check your needle and seat. Just the smallest amount of debris can gum up the works. Clean it. While it's out make sure it moves freely. If it doesn't, then it needs to be replaced. Those little boogers get clogged, stuck, or just hung up with the very small amounts of debris especially if you recently worked on your fuel lines or connectors.
I've had this problem several times in the past. On start up, I would check my fuel pressure and it would be fine (set to 6 or 7), but after a decent drive the pressure would be down to 3. If I ignored it, the pressure would go even lower. If I adjusted it up, then after cool down it would be 10. I took the carb to an expert and he looked at the needle and seat first, and there was a little grain of something that had messed it up, and the needle was not smoothly operating. We replaced it, and all was fine.
I know it sounds odd, but it's really easy to check and fix.
I've had this problem several times in the past. On start up, I would check my fuel pressure and it would be fine (set to 6 or 7), but after a decent drive the pressure would be down to 3. If I ignored it, the pressure would go even lower. If I adjusted it up, then after cool down it would be 10. I took the carb to an expert and he looked at the needle and seat first, and there was a little grain of something that had messed it up, and the needle was not smoothly operating. We replaced it, and all was fine.
I know it sounds odd, but it's really easy to check and fix.
John
You may end up with line pressure if the pump design stops fuel flowing back through it when turned off.
Going by marks description they are a prima donna ,maybe a fuel cut solenoid just at the carby would make it more reliable/consistent.
Jim
You may end up with line pressure if the pump design stops fuel flowing back through it when turned off.
Going by marks description they are a prima donna ,maybe a fuel cut solenoid just at the carby would make it more reliable/consistent.
Jim
Pat
Supporter
John, not sure of the carb you have but you may want to check the float level and seat. You may have flooding issues that are creating startup problems. If it's a Edelbrock carb, you can buy a rebuild kit at most parts stores and it only takes about an hour to take it apart, clean everything, blow WD40 into the passages and put it back together to spec.
If you use two sponson tanks in your SPF, as Jim suggested, you probably have a check valve that stops fuel running back to the pickup lines so your pump simply doesn't flow gas from one tank to the other. So I can see how you'd have pressure after shutdown.
If you use two sponson tanks in your SPF, as Jim suggested, you probably have a check valve that stops fuel running back to the pickup lines so your pump simply doesn't flow gas from one tank to the other. So I can see how you'd have pressure after shutdown.
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