94 STS- Changed FPR and Weird Things Happened

hotrails · #1 (**permalink**) 04-20-08, 03:08 PM

My '94 STS had been starting hard when cold, and I have been through this before with it. Had the FPR changed- last time by the dealer (thanks $300). Changed it on my wife's '98- was easy. So I start in on the '94 this morning. Set up a bit different than the '98. The FPR goes in from below instead of from the top like the '98 and newer. Okay, so I pop the black frame that holds it in, and also hold what appear to be something to do with the coil and spark? (Am I correct?). Anyway, I actually have no problem getting the FPR in. Snaps into place. Of course, I had no fuel pressure, only a couple drops dribbled out...hook up the fuel line and it seems everything is ready to go back together

So, after I replaced the cover and everything was back together (it said don't start the motor w/o the beauty cover in place), I start the car. It immediately races to 3500 rpm! I shut it off. Then start it once more. Again, races to 3500 rpm, kinda stumbling. Shut it off again. I let it sit a minute then try a third time. This time it caught smoothly, and the rpm started climbing but leveled off at 1250. And it stayed there. It was running smooth, but it was idling really high at that rpm. I went through the diag codes but nothing, except the "service engine soon" light came on. So, did I do something wrong, or did I fix one problem and uncover another? BTW, I let it idle about a minute or so at 1250 and when I shut it off the motor was blow smoke around the engine bay. That didn't seem right either. Have 160K on her with no major problems until it the hard cold starts...

**Ranger** · #2 (**permalink**) 04-20-08, 03:26 PM

My guess is that the FPR is not seated properly and is leaking (or you have a vacuum leak). Remove the manifold cover again and turn the ignition on (DO NO CRANK) to pressurize the fuel system and look for any leaks. If that is OK, then start looking for a vacuum leak, especially around the manifold cover. On the '93/'94 it is not a beauty cover, but a functional part of the intake.

hotrails · #3 (**permalink**) 04-20-08, 04:36 PM

Thanks Ranger. I thought I had pushed the FPR in far enough to get seated, but I will go remove the manifold cover (it did seem more functional than the '98s for sure) and recheck.

You mentioned that if the FPR is not leaking or any other fuel leakes, the manifold cover could have a vacuum leak. Where should I check if that's the case? Thanks. The Vaccum link took me to a plumbing website (yours?) so i didn't see that information...

hotrails · #4 (**permalink**) 04-20-08, 05:41 PM

I reseated the FPR, although it didn't seem to be leaking. it is in nice an tight. Put everything back together and started the engine- same thing. It stumbled upon catching and then raced to about 3500 rpm then settling back down to 2000 and then hovering at around 1700 rpm. Still way to high for normal. It didn't do this before so obviously I disturbed something. I don't see any hoses are anything for vacuum. Is the seal entirely up to the manifold cover? I have all the torx bolts down tight ( I don't have a torque wrench or gauge but they were awfully tight when i took them out). I guess I don't know where to check the vacuum at. This car has been so trouble free that even though I have had it since '96, I have never had it do anything like this before or had to troubleshoot it.

**Ranger** · #5 (**permalink**) 04-20-08, 09:53 PM

Spray some Brakleen around the manifold cover base. If there is a vacuum leak there the RPM will rise. That would be the most logical place.

hotrails · #6 (**permalink**) 04-21-08, 08:38 AM

Do you think I didn't get the plenum seated tightly enough when I put the new FPR in? It doesn't appear to have a gasket or anything and it seems that the manifold cover just cinches it down. Can I even run the car w/o the manifold cover on to check the leak with Brakleen? It say to torque the torx bolts down before starting the engine on the plenum...sorry for all the questions but this is different than my '98...

**Ranger** · #7 (**permalink**) 04-21-08, 12:17 PM

NO, you cannot run it with the manifold cover off. If you start it that way it will run WOT and bounce off of the rev limiter. Maybe you tightened it TOO much.

Krashed989 · #8 (**permalink**) 04-21-08, 02:22 PM

Check to make sure the gasket on the manifold cover is properly seated. Sometimes it comes out of its groove in places and when you tighten it down you have a vacuum leak.