2.9 whipple, loss of boost, lean

[MurderedMach]

Ok so I purchased this car from a member here. Ran great the first day I had it home. Next day I noticed the car was hiccuping bad when I stabbed it. Saw the AF was going nuts.

Babied the car home and parked it.

The car drives great under normal driving conditions. WOT it's showing 17-17.8 AF.

Car is pullied for 21-22lbs. Only making 9-10lbs when I stab it.

Battery voltage looked alittle low so I replaced alternator and tested battery....voltage still looks a bit low but not sure how that could be a culprit anymore.

Car has triple external 255 walboros which have about 1000 miles on them. It is a return fuel system and I'm showing great pressure at the gauge on regulator. (45idle and mid 50's when reving it)

Fuel filter is aeromotive and looks great.

Has 105lb injectors. Like mentioned, car ran great when I got it home, took it out for a couple passes with some buddies and went to shit.

Any input would be helpful.

 

[MalcolmV8]

Well since it was running great initially something has broken down. You mentioned three pumps and they're external which I imagine makes it easier to get to and test. Might start there. I know you have fuel pressure idling and revving it but that just tells you one pump is working. My car for example can go WOT in 1st and 2nd on just a single DS405 pump. It's midway through 3rd gear and up I need the second pump.
Maybe disconnect two pumps at a time and verify each pump is working.

Assuming all pumps are working get a pressure gauge hooked up and see what pressure you have when it goes lean.

Also check the basics like vacuum leaks. Any hoses popped off under hood etc. Use some carb spray and check all spots for possible leaks.

BTW be very careful with 17 AF at WOT. As soon as you stab the throttle and see it swinging lean let out immediately.

 

[MurderedMach]

I've gone over it front and back for leaks. The loss of boost is what's making me scratch my head.

I'm gonna try to pumps today

 

[MalcolmV8]

I missed that part. I thought you were saying 9 to 10 lbs when you lightly stab throttle. I see now you mean WOT.

 

[f2hatch]

I know a few guys have had to replace that internal bypass valve in the Whipple. Every guy I know that has had to do it was on 2.9's. might help

 

[MurderedMach]

Is that the black valve on the back?

Would that cause it to run lean?

 

[MurderedMach]

Culprit:

2 shot fuel pumps.

Thanks guys

 

[c6zhombre]

Damn!?! I'm assuming this was on the E85 tune? If so, this is the 3rd or 4th example of an E85 s/c ford go way over 1.00 lambda WOT and not blow into a million pieces. Amazing :bowdown:

 

[MurderedMach]

Yes. It saw 17.0 a lot while trying to figure this out

 

[MalcolmV8]

Culprit:

2 shot fuel pumps.

Thanks guys

Glad you got it. Wonder how long it's been running on 2 pumps before a second one died. Surely two pumps didn't die simultaneously.

 

[MurderedMach]

Glad you got it. Wonder how long it's been running on 2 pumps before a second one died. Surely two pumps didn't die simultaneously.

I'm thinking when I got it one pump was hurt bc it would spike lean every now and then but not terrible.


Only issue I'm having now is my autometer boost gauge is still reading 9psi, but great vacuum.....but it's making more than 9lbs lol