just installed p600b and having tuning questions!

**K.C.90gt** · 04-14-2003, 02:09 PM

alright, first off here is my setup: ATI p600B 14lbs through 3-core IC, into 75mm Pro-m MAF, with aeromotive AFPR, 36lbs injectors, walbro 255lph intank, and a fmu (dont know what disc are in it)..
here is the problem:
When I start the car the fuel pressure goes up to 100psi.. it idles ok until it warms up.. once its at normal oper. temp it stalls at idle and CE light flashes on off, I have to give it gas to keep it running.. when I drive it and hammer it the fuel pressure drops down to like 90 or 80 then back to 100 when I let off.. Its running really rich and I tried adjusting the fuel pressure with vacuum of and it wont change from 100.. I know thats not right or safe but I cant get it to change..
I was told to take the fmu off but I want to know what I have to do to run it without an fmu.. can I just pull the vacuum line off the fmu or do I have to diconnect it completely from the fuel lines and all..
also I have NGK v-power plugs one range colder all set to .05 gap.. I was told that was ok and that .035 isn't nessecary with MSD.
PLEASE HELP ME OUT AND TELL ME WHAT I CAN DO TO GET THE FP DOWN AND IDLE RIGHT... THANKS FOR ANY HELP

**paluka21** · 04-14-2003, 02:27 PM

Originally posted by K.C.90gt
alright, first off here is my setup: ATI p600B 14lbs through 3-core IC, into 75mm Pro-m MAF, with aeromotive AFPR, 36lbs injectors, walbro 255lph intank, and a fmu (dont know what disc are in it)..
here is the problem:
When I start the car the fuel pressure goes up to 100psi.. it idles ok until it warms up.. once its at normal oper. temp it stalls at idle and CE light flashes on off, I have to give it gas to keep it running.. when I drive it and hammer it the fuel pressure drops down to like 90 or 80 then back to 100 when I let off.. Its running really rich and I tried adjusting the fuel pressure with vacuum of and it wont change from 100.. I know thats not right or safe but I cant get it to change..
I was told to take the fmu off but I want to know what I have to do to run it without an fmu.. can I just pull the vacuum line off the fmu or do I have to diconnect it completely from the fuel lines and all..
also I have NGK v-power plugs one range colder all set to .05 gap.. I was told that was ok and that .035 isn't nessecary with MSD.
PLEASE HELP ME OUT AND TELL ME WHAT I CAN DO TO GET THE FP DOWN AND IDLE RIGHT... THANKS FOR ANY HELP

You can plug the vaccum on the FMU, it will stop it from spiking under boost. Are you certain you are adjusting the FP correctly? what is the fp w/ the vaccum on?

Dan

**K.C.90gt** · 04-14-2003, 02:41 PM

do I need to plug the vacuum on the fmu AND the line that went to it?
I adjust the AFPR by disconnecting the vacuum line from the afpr and capping the line that went to it.. than I loosen the lock washer thing and take the hex wrench and turn it left or right..
by the way the fp is 100 (maybe more.. gauge only goes to 100) with or without the vacuum hooked up to the afpr.

keep the replies coming please.. I need to drive this thing now.. having to bum rides sucks.. HELP!!

**paluka21** · 04-14-2003, 05:42 PM

Originally posted by K.C.90gt
do I need to plug the vacuum on the fmu AND the line that went to it?
I adjust the AFPR by disconnecting the vacuum line from the afpr and capping the line that went to it.. than I loosen the lock washer thing and take the hex wrench and turn it left or right..
by the way the fp is 100 (maybe more.. gauge only goes to 100) with or without the vacuum hooked up to the afpr.

keep the replies coming please.. I need to drive this thing now.. having to bum rides sucks.. HELP!!

There should only be one vaccum line going to the FMU, this is the one you need to plug up. Leave the fuel line alone however, it will be fine, as I have done this before.
Ok, your adjusting the FPR correctly, is the fp 100 even w/ the vaccum on?
If you tighten it down the FP will increase I believe, and if you loosen it the fp should drop. ( I may be wrong, its been a few years )
If you adjust it either way, and you fp is still over 100, then you might have a bad fuel regulator.

Dan

**RI lx** · 04-15-2003, 12:57 AM

I think you have the FMU installed with the lines reversed. Check the instalation

**K.C.90gt** · 04-15-2003, 09:08 AM

alright I went out last night a tried a few things.. heres what I did:

I disconnected the fmu vacuum line and capped both the fmu and the line that went to it.. FP was still at 100psi at idle..

I tried adjusting the afpr all the way out and it still was at 100psi...

I tried rotating the MAF.. still didn't change anything

I tried resetting the computer ... still didn't change from 100 psi..

I checked to make sure the fmu was hooked up right.. the vacuum line was hooked up from the fmu to the vacuum tree on the firewall.. thats good I think

I checked to see if there were any kinks in the vacuum lines around the AFPR and FMU.. everything looked good...

I checked one of the brand new spark plugs that I put in 2 days ago and it was PITCH BLACK... of course I'm running too rich..

I dont know what else I can do to get this thing down in Fuel pressure... Does anyone have any other suggestions of what I can check or adjust to get this thing right? should I try and disconnect the stock computer and run it at idle to see if it is that? What else.. could the Aeromotive AFPR be bad or something???

please keep the replies coming.. this is really bumming me out :(

**WA2FAST** · 04-15-2003, 10:01 AM

Originally posted by K.C.90gt
alright I went out last night a tried a few things.. heres what I did:

I disconnected the fmu vacuum line and capped both the fmu and the line that went to it.. FP was still at 100psi at idle..

I tried adjusting the afpr all the way out and it still was at 100psi...

I tried rotating the MAF.. still didn't change anything

I tried resetting the computer ... still didn't change from 100 psi..

I checked to make sure the fmu was hooked up right.. the vacuum line was hooked up from the fmu to the vacuum tree on the firewall.. thats good I think

I checked to see if there were any kinks in the vacuum lines around the AFPR and FMU.. everything looked good...

I checked one of the brand new spark plugs that I put in 2 days ago and it was PITCH BLACK... of course I'm running too rich..

I dont know what else I can do to get this thing down in Fuel pressure... Does anyone have any other suggestions of what I can check or adjust to get this thing right? should I try and disconnect the stock computer and run it at idle to see if it is that? What else.. could the Aeromotive AFPR be bad or something???

please keep the replies coming.. this is really bumming me out :(

In reply to your last attempts..

Disconnecting the fmu vacume line takes out the possibility that the line could have been hooked up wrong in any way.

Adjusting the regulator would be the next step... you said you adjusted it all of the way out... did you try the other way?

Rotating the MAF has nothing to do with fuel pressure... fuel pressure is strictly mechanical.

Again, fuel pressure is mechanical. Resetting the computer would do nothing.

You having the FMU hooked up to the vacume tree is just fine.

Kinks in the vacume line wouldn't make it sit at 100psi. all of the time, but always good to check that anyway.

I'm still trying to figure out why you would "hammer it" when it is working as odd as it is, but whatever... either way, it sounds to me that something is hooked up backwards or simply malfunctioning.

The way that the regulator works is it lets a certain amount of fuel through the return line back into the tank and that is what creates the pressure. The more you press the accellerator, the less vacume there is in the intake no matter weather it is forced or naturally aspirated. The less vacume present in the intake, the more "pinched" the return line to the tank becomes... causing the fp to go up. Fuel pressure regulators only work off of vacume (except for special "boost sensative" regulators)... and that is where FMU's come in. They aren't effected by vacume at all... only by boost (they work exactly the same, just opposite eachother). So when pressure is present, it respectively "pinches" the fuel line even more. That is why FMU hooks up to the return line for the fuel. It restricts fuel flow back into the tank even more under boost to up the fuel pressure above what the regulator can do.

I don't think it is possible to accidentaly hook the FMU to the send line from the tank, or if that would even effect it how it is, but that is something to look at. I beleive the send and return use different size connectors anyway to eliminate that possibility, but it's worth looking at.

I don't think it is possible to install a regulator wrong either, I am pretty sure they only install one way, but that is something else to look at.

My first guess would be that something with either the fmu or especially the regulator is screwed up. It sounds to me like the regulator for some reason is working backwards from what it should be.

To troubleshoot which one is the problem... removing the FMU from the fuel line will tell you right away which one it is. That would be my first mode of troubleshooting.

Please keep us updated as to what you find out.

**Nasty Notch** · 04-15-2003, 10:11 AM

I have heard before that if the fmu lines are reversed, this problem would occur. I would check the fuel line connections.

**SnakeIs** · 04-15-2003, 10:55 AM

I think the regulator is bad, did you get it used also? try taking it off and putting your stock one back on and see if the problem goes away, if that doesn't work really check how the FP guage is hooked up as I said over on stangnet, something is definitley wrong!

**Sybersport** · 04-15-2003, 12:18 PM

I agree, check the FMU fuel lines. You may have them hooked up backwards

**RI lx** · 04-15-2003, 12:21 PM

If the lines are reversed (the FMU hooked up to the return line, but fuel routed in the wrong direction through the FMU) it will produce the problem you are having. Relieve the FP, and disconect and reverse the lines at the rail.

Pulling the vacumn scource would only disable an FMU thats working right. The reason you can't control the FP at the regulator is because the FMU is pinching off the return, because its installed wrong, or broken.

**Nasty Notch** · 04-15-2003, 03:46 PM

Exactly!!!

**K.C.90gt** · 04-15-2003, 03:47 PM

the aeromotive fuel pressure regulator is brand new and the fuel pressure gauge is brand new too.. its the full sweep eletric kind that has a sending unit attached to the schrader valve and plugs into a harness wire into the gauge..(only one way to hook it up) so I think the gauge is accurate..
When I get home I will check the fuel lines on the fmu.. how can you tell for sure which line is the return line? The guy who I bought this from helped me hook everything up and he told me which lines to hook the fmu up to

thanks again