Is it my fuel pump?

[BftSupra]

I have a walbro and an afpr setup which has been fine for 3 years.

A couple of times in the last week, I have tried to start my car and it turns over nicely but doesn't hit a lick. I get a ride and when I come home I check for codes, nada.. Try it again and it starts up fine and runs fine. Couple of days later same deal, spins nicely doesn't fire. check codes, all clear. look at fuel pressure with key on and nada, even after spinning it over. I should have about 40psi if the pump is working. After checking codes, it starts again. I am thinking the fuel pump is not kicking in, but when it runs and I have driven it some it works fine for the rest of the day.

The other issue I am having(related to this?) is that when I boost i get a fuel cut like cutoff, but no CEL codes. I put a wideband on it and when I hit the cut off, the a/f goes through the roof(20 or so). I am afraid to boost at all now. Is this my walbro giving it up and not making enough pressure to squirt appropriately?

Any other theories?

 

[jdub]

Here's the TRSM procedure to check the fuel pump:

http://www.cygnusx1.net/supra/library/TSRM/fi/FI_071.html

You problem could very well be fuel related. If your AFR goes high under boost, that means lean...not good...that causes detonation and or melted pistons.

 

[BftSupra]

Tsrm is good stuff. I had the starting problem again yesterday and got a code 51. Turned off the a/c and it started up. Not sure what to do with this, but starting it with the a/c off is a good bet for now.

Still not sure where to go with the boost problem. I would have to go to the dyno to watch the fuel pressure gauge for loss of pressure at boost. guess I will go look for a boost leak again.

 

[jdub]

You will always get a code 51 with the AC on
It will also appear anytime the gas petal is depressed.

 

[antman]

sounds like a bad pump or bad connection to the pump. what boost pressure are you running?

 

[theDon]

did you do the 12 volt constant mod for the fuel pump? that may explain the WOT A/F jump? stock will go from 9v to 12v and can really throw off tuning.

 

[BftSupra]

did you do the 12 volt constant mod for the fuel pump? that may explain the WOT A/F jump? stock will go from 9v to 12v and can really throw off tuning.

Unaware of this mod. documentation?

 

[BftSupra]

sounds like a bad pump or bad connection to the pump. what boost pressure are you running?

I was running 19, now it is cutting out at 14.

 

[antman]

i would start were jdub suggested.

 

[theDon]

yeah don't worry about the 12v mod quite yet, but it's something I recommend IMHO. Pleanty of info via search function, and it's a very easy "mod" if you will. Some will argue against it, some will also say to rewire the fuel pump etc etc. Enjoy

 

[BftSupra]

Well, i got the same old no start this morning, and jumped the pins to test the pump. it immediately popped up to the 45 psi it was set at. Then the car started right up and ran fine. Seems like maybe the pump is not being switched on every time I try to start it. Intermittent failure, my old nemesis.

I turned off my profec B spec II BC and ran with only the wastegate today. Boosts fine though it's limping along at 10 psi.
I guess I am kinda spoiled from running 18 psi.
In an act of shear desperation, I read the BC manual and it seems that everytime you change the boost you have to re set the start boost and gain % functions. This all started when a guy with a dyno told me he could really fix up my boost to be faster and more better... I think I will re-init the BC and start over with it. I can re-tune it myself now that i have a w/b.