fpr problem after jump start

[tweak666]

I'm not sure if these problems are related. Yesterday, before I drove to school, I bumped up my fuel pressure a couple psi (last base setting was 38 psi with vaccum), to richen up my upper rpm range. Everything was ok, went to class, came back to the car and it wouldn't start cause of my starter. I got a jump start, and just before I was going to get on the highway, I turned on my foglights, and things got dodgy. my afr went a little lean and the car wasn't responding like it usually does. I took a different route home so I could keep the load low. The afr's wavered between 15.5 and 16.3 at idle, steady and rythmically. under load they stayed pretty much the same, and when I took my foot off the gas to brake, afrs would drop to between 12.7 and 13. Car sputtered and bucked under light acceleration and the BOV would release air sometimes without taking my foot off the gas. Once I got home, and turned off the headlights and foglights, the idle changed, and the afr's steadied a bit. I opened the hood, and the FPR gauge was going crazy, the needled was bouncing between 20 and 25 psi. I pulled the vacuum and pinched the line with no change. Previously the needle never bounced, and i've never had fuel pressure that low. Did the jump start mess up something electronically, causing maybe the pump to go bad? could it be the computer? Could it be something wrong with the lighting?

 

[grimreaper]

you jump the b+ to fp relay in the diag. box?

 

[Facime]

when you had to jump it you said because of a dodgy starter, but starters dont (usually) suddenly work better with a jump start. Is it possible your battery was so low (dead) that the ECU reset? That might explain the odd running condition upon restart, though it probably should clear up by the time you got home. Its possible your alternator is going out, thus not charging the battery and also not providing enough output for the ECU and other electricals.

Take the alternator in and have it bench tested.

 

[Supra87T]

the needled was bouncing between 20 and 25 psi.

Have you checked your fuel pump to make sure it is receiving proper voltage?

 

[NeatOman]

Take the alternator in and have it bench tested.

:thumbup:

 

[suprabad]

Sounds like a voltage or ground problem, that's where I'd start looking.

 

[tweak666]

Update. started the car today, checked the alternator, its good, fuel pressure is back to normal. The car ran like nothing ever happened, till i turned on the headlights. there was a quick spike in the afr to the mid 16's then back to normal.

 

[grimreaper]

bust out the voltmeter and have at it.

 

[tweak666]

I'm confused as to where I should start looking. Should I start at the headlights and work my way up the harness? or should I start at the fuel pump? If I think the lighting system is the problem, that would be the logical place to start, right? Is there info in the TSRM that deals with troubleshooting voltage problems?

 

[92nsx]

It still sounds like your alt./or battery is not up to par.
Try this: check voltage at battery,(starting point) next start engine and check the battery with a load tester and check voltage. See that you alt/battery is up to par. If you don’t have a load tester turn on every acc. (wipers, heater, lights, fogs, radio, defrost, EVERYTHING) and make sure the voltage doesn’t drop to much, if it does then the either the battery or alt. is shot, unless less something has a HUGE amp draw, like 5,000 watt head lights or something like that.

I'm no expert but this is me thinking out loud here on this: If my fuel pump has less voltage then it should it just seems logical that it won’t pump as much causing a lean condition. Why would this only happen when I turn on the head light or a have a high amp draw from the charging system? UM.... I need to make sure of this first..the battery/ system voltage never goes under 13.8 volts when engine is running, no matter what the amp draw is.

 

[grimreaper]

start at the battery and alternator. pull your grounds (all of them) and clean the contact points to like new quality, it sounds like your elec. system is getting loaded to heavily with the lights on like the alt is worn.

edit 92nsx beat me to it

 

[V8hntr]

I'm not sure if these problems are related. Yesterday, before I drove to school, I bumped up my fuel pressure a couple psi (last base setting was 38 psi with vaccum), to richen up my upper rpm range. Everything was ok, went to class, came back to the car and it wouldn't start cause of my starter. I got a jump start, and just before I was going to get on the highway, I turned on my foglights, and things got dodgy. my afr went a little lean and the car wasn't responding like it usually does. I took a different route home so I could keep the load low. The afr's wavered between 15.5 and 16.3 at idle, steady and rythmically. under load they stayed pretty much the same, and when I took my foot off the gas to brake, afrs would drop to between 12.7 and 13. Car sputtered and bucked under light acceleration and the BOV would release air sometimes without taking my foot off the gas. Once I got home, and turned off the headlights and foglights, the idle changed, and the afr's steadied a bit. I opened the hood, and the FPR gauge was going crazy, the needled was bouncing between 20 and 25 psi. I pulled the vacuum and pinched the line with no change. Previously the needle never bounced, and i've never had fuel pressure that low. Did the jump start mess up something electronically, causing maybe the pump to go bad? could it be the computer? Could it be something wrong with the lighting?

I am having the same problems. The FP oscillates from 30-40 or 40-45 at idle and when I drive the car and put even a little load on it, it starts running lean and I boost it runs mega lean and caused the engine to overheat which is very bad. The engine does not rev up under load it just sputters. I drove it home under very little load. The fuel pump Walbro 255 and Aeromotive AFPR are only 2 years old. Maybe the fuel pump relay.

 

[grimreaper]

are the gauges on the fpr? and are they liquid filled, if so there is a rubber grommet on it that needs to be removed to vent the gauge to get an accurate reading. make sure the opeing is facing up (obviously) so it doesnt leak all the oil out of the gauge!