I cant get the car to stay running, and i cannot figure out why.

the symptoms:

Car will start every time, jump to about 2k, and sit there for a few seconds. It will then procede to just drop RPM smoothy till it just dies. If you try to nail the gas, it dies. You have to feather the gas pedal to keep it running.

If you let it sit for a while, and try to start, the car will stay running. I had it going for about 5-7 min today. If you touch the gas, it dies.

I have basically changed everything over the winter, so its going to be hard to track down the problem.

Here are the mods i performed:

-dual walbros
twin relays with direct 12v power, grounded to the battery
-550/1600
-aeromotive FPR set at 40lbs.
-I am getting a steady fuel pressure according to the gauge.
-xst04s kit (shouldnt make a difference)
-blocked off everything emissions/stock related
-AEM CD2i
-Power FC with a BRAND NEW engine wiring harness
-removed double throttle system

I have the stock map loaded into the PFC, that should not be the problem.

I dataloged one of the cars cycles, and nothing looks out of place. Good 13.5v power untill it dies...nothing out of the norm...

I cannot find any obvious vaccume leaks. I sprayed some carb cleaner around the manifold and the idle did not raise any.

Grounds are all attached and look fine.

the 550's are not leaking.

I cannot think of anything that would make it run like this. Please help

 

could be something simple as changing the fuel filter, maybe reset your computer..

try those basics before you go crazy

 

I have two new fuel filters. Computer has been reset.

 

OK, when the car is running the fuel pump relays should never click off right? well mine do. I'm guessing thats my problem. I will redo and post results.

 

i was about to say that, i would def check that

 

No dice. Replaced relays with the same results.

 

I'm going to get a timing light tomorrow...see how that checks out.

 

Something doesn't jive here. In your original post, you said
I'm guessing you mean to 12v through your ignition? The relay is not your problem, it's how it is energized. You may want to use the stock FPR power source.

 

Yeah, the relay is turned on by the original fuel pump power wire. There should be no problem there.

 

Yeah, the relay is turned on by the original fuel pump power wire. There should be no problem there. I'm just saying the pumps are seeing +12v

 

Let's look at it this way, the original power source was designed to supply enough current to run one relay, you are now running 2 relays in parallel from the same power source.
Here's a suggestion, reconnect the power to your fuel pump relays, take them directly from the battery (temporarily), crank up the car and see if you are still getting the same symptoms, if not then you know the original power source cannot provide enough juice to run 2 relays simultaneously.

 

Your thinking about it all wrong. The original power source is NOT supplying power to the pumps. It is now ONLY a trigger to turn ON the 2 relays which get their power from the battery. Myself, Dragon and Igy all run our twin walboro's with the stock fuel pump power wire as the trigger. There's no draw on that wire whatsoever. It's sole purpose is to turn on our fuel pump relays.

 

Yeah, what he said. I know the wiring to the pumps is not the problem.

here is the write up i used.

 

 

You did not read my post correctly.
Lesson on basic electronics:
A relay consists of 2 basic parts: 1. a coil (inductor), when energized acts like an electromagnet. 2. Single or multiple contacts that are closed (connected) or open when the coil energizes.

To energize the relay, there must be sufficient current passing through the inductor. (your so called trigger). I beg to differ on your comment of having no current draw on the "trigger". It may have worked on your car, but it is very conceivable that the wiring conditions on other peoples car do not supply enough current to energize both relays.

As mentioned in one of the posts, the fuel pump relays are not energizing. There is only 2 possible conditions that can cause that (given the relays are good), 1) No current, 2) Not enough current. In either case it can be very easily tested.

Of course I could be wrong, it has been 12 years since I got my masters in EE.

 

I'll give your 12 to the switch a try tomorrow, but both relays are turning on...i can feel/hear them both click..

 

I have talked to freeman (via AIM) quite a bit about his FD. His single walboro pump was running fine off of the stock fuel pump power wire so I would assume that if it was drawing enough current to supply power to the fuel pump previously, then it would have enough current to "trigger" two measily relays.

Either way, simply running a wire off of the battery to the trigger on the relay would eliminate the wire in question as a possible cause of failure.

 

Are you still using the stock map sensor?I would check to see if it is reading correctly.My car would start and cut off because the power fc was not reading the Apex 3 bar correctly(I think it was reading -462 without the car even running)

 

OK, when you set your FPR to 40, are you setting it to 40psig @ atm. or 40 under vaccume?

If you set it to 40 @atm. you are foing to run way lean under idle. Your FPR should be a 1:1 ratio. You need to set it to 50psig at atm. When you start the car, you should be at about 38-42 psig. Under boost, you go 1 up from 50psig per 1 pound of boost.

Another thing you might want to check is the wiring of the fuel pump ballast resister under the brake booster. If it becomes dammaged or wires broken, you will get fuel for start-up but, you get nothing after that.

Given what I have heard from your question, this is where I would start.

Adam

 

Yeah i set it at 50ish atm, so it dropped to 40 when it would start up.

I will give the ballast reisistor a look...

 

Yes i have the stock map sensor. I need to buy a 3bar GM one...

I have a extra stock sensor i will swap in to see if it makes a difference.

 

bobby, I have a timing gun... let me know if you need to borrow it.

If you want i can also let you borrow one of my widebands so you can see if fueling is the problem.

good luck

Mike

 

i'll be working on it this evening, just giving her a little bump for now.

 

fubared filter to the map sensor. Now to fix the hunting idle...

 

LMFAO. Told you I could get the idle fixed!