94 mark8, where's the code

46callaway said:
You can get a Walbro 255lph real cheap, around $100 bucks. Dropping the tank is easier than you think just make sure there's not much gas in the car. Gas is heavy.
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Nate and I use Walbro carb's on our KT100 Yamaha powered race karts. At least that's a name I know and trust!:D
 
Ok....after you cycle the key a few times and its NOT holding pressure, you have one of two issues going on. NOW were getting somewhere! This is what we had kinda figured in the beginning.....

A bad fuel pressure regulator(pretty cheap/easy to change).

A bad fuel pump(kinda cheap and kinda easy to change).

I'd start with the fuel pressure regulator, its located on the back of that same fuel rail where the shradder valve is. It has a vacuum line at the top of it. Has 3 bolts holding it on and would be the cheapest place to start.

If you have some questions about dropping the tank....check out my thread, dropping the fuel tank is covered, and its pretty easy. The fact that the car drives is VERY good because you can run it low and the gas tank will be lighter.

http://mark8.org/vbulletin/showthread.php?t=15292
 
Thanks!

I talked to the guy's at work, they lent me a fuel pressure guage, but they said the same thing , either pressure regulator or pump. I'm still pulling for the regulator!(like you said , easy.)
I'll post as soon as I know what's what.

Thanks again for your help!!
 
We replaced the fuel regulator today(at least thats what I THINK I replaced). I could not find a three bolt regulator on the drivers side at the end of the fuel rail. There was nothing there that I could see. Where I DID find a regulator was about half way on the RIGHT side rail. It has two bolts holding it on and a vacuum line on top of it. One of the lines going into the manifold said "High pressure fuel" on it.
Before I repalced this part the fuel pressure was about 14 psi and that was not until the gas pedal was pushed while turnning over the motor. Now the fuel pressure is about 20 psi while turnning over the motor without pushing on the gas pedal.
The engine still has some driveability problems though when cold and stumbles a little when warm and hard on the gas.

Do I need to use the code reader to clear the OBD codes or can they be cleared by disconnecting the battery?
The check engine light still comes on and goes off while driving.

Thanks guy's!!!

Scott
 
You can clear the codes by disconnecting battery. Left side of car is the drivers side....right side is passenger side. Side is determined on ALL vehicles by sitting in drivers seat!
 
Sorry about that...I thought it was like the Mustang style that have 3 bolts. You did replace the regulator, its a bell shaped thingy with a vacuum line on top.

Does the car still hard start, or does it start easier? Also....does it HOLD pressure after you let it sit for a while?

The CE light coming on/off is your car telling you something is still wrong(could be the same codes). Clear the codes by disconnecting the battery for 10 minutes, and turn on the headlight switch after you pull the battery terminal, this will completly discharge any residual power. After you re-connect it, you have to drive it for awhile so the ECU can "relearn". If the check engine light comes on at ANY time, pull the codes and we'll go from there.
 
Mark VIIIs have 2 styles of fuel pressure regulators: 2 bolt and 3 bolt. I believe the early style was the 3 bolt.

Stock pressure is 39 psi. Fuel pressure is measured with the vacuum line disconnected from the regulator.
 
Ohhh...see I'm not going crazy, haha.

Yeah, I didn't think to ask about the vacuum line. Like JP said, check the pressure with the vacuumm line OFF and the car running.
 
Well we check the fuel pressure with the vacum line on and it was about 21 then we pulled the vacum line and it stayed the same, when my dad reved up to about 2000 rpm the pressure went down to 20.

we havent cleared the codes to your instructions yet.
 
Well...if the pressure didn't go any higher, I'd say its time for a fuel pump. :embarrassed:
 
Kinda what I was thinking too, but didn't relly want to go there.:( I'll keep you posted, this one might take a while to do.
 
i got a fuel pump at napa, my buddy who just happens to work for ford is going to come over tomorrow and help me with the instalation.
 
DSC_0017-1.jpg
[/IMG] dave and i loosend up the straps to the tank.
DSC_0018.jpg
[/IMG]took off the bolts to the hangers of the muffs.
DSC_0021.jpg
[/IMG]took the exhast off.
DSC_0023.jpg
[/IMG]then we disconected any hoses.
DSC_0029.jpg
[/IMG]took the old fuel pump out and replaced it,
DSC_0031.jpg
[/IMG]and whalla we're finished.

then we just put the tank on and all the hoses and everything. i of course wanted to hear the car with no exhast on so i fired it up with no problem(this thing sounds mean!!!) dave suggested that i just go to napa auto parts and get a down pipe for the exhast.

anyways car starts fine, check engine light doesnt come on anymore and the car actually has some power!!!:eek:

thanks so much you guys, i couldnt have done it with out your advice.
if theres and sort of run in so-cal let me know and we can meet up and ill get you guys some lunch or something. haha:D
 
The hose from the pump to the tank was deteriorated! fuelpump replaced! it came with a new hose, fuel pump couldn't pump the fuel because it was poring back into the tank(the litlle that did get pumped took forever to get it started, and now we know why it sputtered going uphill! lol) at the top of the hose (full of holes), that's why it ran better on a full tank!!! now runs great! starts great, and no check engine light!! Thanks again for all the info you provided him! :)
 
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