Tuning and Problems... HELP!!!!

[gixxer750]

OK....I've been having serious issues with my car. I'm going to try to give as much info as I can.

Engine and Fuel Management:

Emanage Blue with injector harness, 550 RC injectors, Holley(Walbro) 255 lph hp, Aeromotive FPR @ 42 psi with vac line off, lex AFM housing

Engine mods

.040 over Wiseco Pistons, stock race prepped rods, cometic 2 mm HG, UR Cam gears, new everything internal, minor port cleanup and bowl cleaning on head, heavily ported Exhaust manifold.

Turbo is a turbonetics 62-1 bolt on, full hardpipes, aftermarket intercooler, cooleze downpipe.

12 volt mod is done for fp.

BRAND NEW wiring harness.



Problem I'm having is that I had two fuel pumps die in a row. The first one was a walbro, I'd had it about a year and a half or so. I bought an ebay one to replace it. The ebay one was a dead one out of the box. I drove the car for five minutes with it in. Every time I tried to boost it would go lean. The car started stumbling at idle and I popped the hood. I watched the Fuel Pressure on the gauge go to zero on the FPR. The fuel pump was making funny noises at the time.


So, then I order another "holley" walbro from advance so I could get it next day(it really has the walbro logo on the side of it).

I put it in, and it worked great today. I took the car out and tuned it for a while, and got my tune just right at 11.9 AFR. Well, when dark got here, the temp dropped 20 degrees, and now my car goes almost 15.0 under boost(just once) at about 5k rpm.

Is this just 40 degree air or another FP dying or what? I'm about sick of dropping my tank and paying for dead fuel pumps.

Also another thing, I have the lex and 550's with my emanage. I'm having to pull about 32 % out of the AFM signal to get 11.9 AFRs..... Why?

 

[Intothenight19]

Sounds like a bunch of bad fuel pumps. Try going with a bosch or since you seem to be going all out with e-manage and all, you could go with an external aeromotive pump. Sounds like a bunch of bad walbros to me, I've heard that they have been known to fail, that they are a hit or miss thing. Hope you find the problem!!

 

[gixxer750]

Well, I've got one I can warranty now, no matter how many times it takes. I'm just gonna buy an A1000 and do my whole fuel system.

 

[Suprawannabe]

That pretty weird to have two bad pumps in a row, have you though about wiring issues?

never mind I just read "BRAND NEW WIRE HARNESS"

 

[tubbie]

But the brand new wire harness, is that the engine harness? Could be the power wire going to your fuel pump is bad. Not supplying enough current to the pump.

 

[malloynx]

you need a diagnostic approach to this issue.

first... walbro fuel pumps are known to have poor QC. you could have gotten a bad one from the factory.

2nd.. temp drops play a HUGE factor in boost. if your running a MBC your psi will go up. colder the air= more dense; which means leaner condition. however i think going from 11.9 to 15.0 is extreme.

If you have access to a DVOM, check the fuel pump ckt. get the available voltage to the pump, perform a voltage drop test of the positve side and the ground side. that should get you an ideal if you have high reisistance in the wires, interminent shorts, etc...

when i back-probed my FP chk with the car running i was seeing about 12.8volts going to the pump which is pretty good.


also remember; if your doing a voltage drop test less than .5 volts is acceptable. anything over that and your wiring is questionable.

 

[gixxer750]

I'm using an electronic boost controller. Greddy Profec b spec II... Boost stayed at 14 psi.

I will check the FP voltage today, and see what comes out of that.


One other thing I need to add. The AFM thats on the car test good, and I don't get codes. However, if I put it on my 89 it makes the car run bad.

Wonder if the intake temp sensor in it is toast?

 

[Suprawannabe]

you need a diagnostic approach to this issue.

first... walbro fuel pumps are known to have poor QC. you could have gotten a bad one from the factory.

2nd.. temp drops play a HUGE factor in boost. if your running a MBC your psi will go up. colder the air= more dense; which means leaner condition. however i think going from 11.9 to 15.0 is extreme.

If you have access to a DVOM, check the fuel pump ckt. get the available voltage to the pump, perform a voltage drop test of the positve side and the ground side. that should get you an ideal if you have high reisistance in the wires, interminent shorts, etc...

when i back-probed my FP chk with the car running i was seeing about 12.8volts going to the pump which is pretty good.


also remember; if your doing a voltage drop test less than .5 volts is acceptable. anything over that and your wiring is questionable.

aaawww snap, you sound like Mr. Brown :biglaugh:

Wonder if the intake temp sensor in it is toast?

Im guessing you mean Maf since you not running speed density http://born2drv.com/TSRM/Service Manual/FI/FI_096.GIF

See if its still up to par.

 

[gixxer750]

It tests good..... but like I said, makes my 89 run like shit.

 

[Suprawannabe]

It tests good..... but like I said, makes my 89 run like shit.

Well if it is within specs it should be good. I would concentrate on fixing your fuel pump problems first, like Malloy said check the ground and power side of the circuit.

If you have two Supras, and really want to eliminate a faulty pump problem take the one out of the 89 and run it will low boost in the other one and see how it reacts or vise versa.

Either way you should be able to tell were your problem lies whether it be the wiring or pump.

 

[gixxer750]

I'm going to try that, and the afm swap between the two cars.