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c101guy
10-06-2014, 12:10 PM
When cold starting my 1990 SC 5spd (stock with exception of CAI), the car turn over, but sputters and stalls for 2-3 attempts, then starts up and idles / runs fine.
I've been given some good insight that it is most likely fuel related - ie a clogged fuel filter or failing fuel pump that does not initially build enough pressure - but figured I would throw it out to the crowd as well in case someone has had the same issues. Thoughts?
Thanks

aroot1
10-07-2014, 09:36 AM
you could try cycling the pump a few times WITHOUT starting the engine. Just turn the key to the run position, wait a few seconds, turn it back off, repeat, then try starting it. That will cycle the pump, if it is a pump/pressure issue like you believe, that SHOULD cause the pressure to build and start on first try. Another thing to try to verify this would be get it running, but still cold (a few seconds, til idle stabilizes) shut it off, then immediately restart, it should still have good pressure, and restart first try. If you have a question about the filter, I say change it, cheep and easy. BUT if you r questioning the pump out put I would b very cautious about getting into boost, running lean under boost because of a bad pump will quickly end up with more damage, ie headgaskets or worse

Adam

c101guy
10-08-2014, 07:34 PM
Thanks.

It is odd. Turns over and barely runs / stalls a couple of times then fires up and runs like a champ. Restarts are fine unless a few hours go by.
So far the responses center around fuel filter, fuel pump and cam position sensor.

Will do the fuel filter this weekend. Purchased a CPS just in case. If fuel filter, should I go back with OEM or upgrade (Note: I do plan on putting a late model supercharger on soon).

Thanks again

figulaz
10-08-2014, 09:03 PM
Do you have old contaminated gas in the tank? Vac leaks? Was it running well or is it a project/startup? Any work done on the car before the issue? Check engine light/ codes?

c101guy
10-09-2014, 01:16 PM
Thanks,

I realized that in my thread I asked about an OEM fuel filter if I am installing a rebuilt late model supercharger with an early model pulley (assuming a 3% overdrive) when in fact I meant fuel pump. Will the early model fuel pump work with the late model SC or will it run lean (not changing the MAF or anything). If so, what is the preferred flow rate when replacing the pump?

With respect to the car. It is my daily driver. Fresh gas, no motor work, no obvious vacuum leaks. Once it starts it runs and idles just fine. I did try the cycling of the key on and off about three times prior to starting and it did seem to help.

figulaz
10-11-2014, 08:41 PM
For a fuel pump you should upgrade to something like a walbro 255 lph gss340 a lot of guys seem to be getting the aeromotive pump too. Either way make sure you get the correct one for forced induction with the correct sock. make sure to get it from someone reputable. There are low pressure units that plug in but can make you go lean...there are also knock offs on ebay that don't flow a well. Contact xr7 Dave, supercoupe performance or spinning wheels for the pump. Once it's running good. Get the blower injectors and a tune all at once.

c101guy
10-13-2014, 11:52 AM
Thanks, I appreciate the information.

c101guy
10-18-2014, 01:14 PM
Well, I replaced the fuel filter and that did not solve the issue. According to the forum, the next step is either the cam positioning sensor or the fuel pump. The cam positioning sensor is obviously easier to replace, but is still a pain to get to - can't get my hand to the bolts, 24 years of grime, stiff wiring harnesses in the way. Before I do this, I wanted to re-ask;

If the car takes 3-4 attempts to cold start, then runs fine and restarts fine unless it sits for 4-5 hours, does this still sound like the cam positioning sensor? Would there be a difference between a cold start and a warm start with this sensor? Does the more likely culprit seem to be the fuel pump (ie. the check valve).

I also have a splice repair to the fuel line under the car that is about 5 years old, has never given me a problem and does not seem to be leaking - could this be a culprit?

I really enjoy the feedback on the forum - I'd be lost without you guys.

KMT
10-18-2014, 01:39 PM
- Yes - at least.
- Maybe/maybe not...depends on if other issues, such as poor wiring, bad grounds, failing EEC and other failed sensors exist at the same time.

Do you have an error code that points to the sensor?

Replace the cam sensor and disconnect the battery several minutes to force the computer to relearn that new sensor.

As for the fuel line, did you confirm pressure at the rail? Does it drop quickly after key off? Did you inspect that repair?

c101guy
10-18-2014, 01:51 PM
- Yes - at least.
- Maybe/maybe not...depends on if other issues, such as poor wiring, bad grounds, failing EEC and other failed sensors exist at the same time.

Do you have an error code that points to the sensor?

Replace the cam sensor and disconnect the battery several minutes to force the computer to relearn that new sensor.

As for the fuel line, did you confirm pressure at the rail? Does it drop quickly after key off? Did you inspect that repair?

I have not checked the residual fuel pressure - what should it be and does it drop off with time or should it maintain the pressure? I assume you check it at the valve on the driver side rail - any specific gauge required (sorry for the seemingly foolish question, but better to ask and be thought a fool than act without knowledge and remove all doubt - haha).

Thanks

KMT
10-18-2014, 02:09 PM
Outside of hitting the release valve on the fuel rail to check, which can be unreliable and maybe dangerous, you'll need a compatible gauge to at least test with - some of us mount a mini fuel pressure gauge right on the rail. Check your local autoparts or harbor freight.

I can shut mine down and still see 20~30# an hour or more later, so you want to know if it drops right away or in a few minutes which would indicate some issue, at least.

Might be line leak or fuel pressure regulator if it does. You can pull the vacuum line off the regulator to check for raw fuel if you can get back in there to work.

Did you check codes? If you don't know how, let the local auto parts store check for you.

c101guy
10-18-2014, 02:17 PM
Outside of hitting the release valve on the fuel rail to check, which can be unreliable and maybe dangerous, you'll need a compatible gauge to at least test with - some of us mount a mini fuel pressure gauge right on the rail. Check your local autoparts or harbor freight.

I can shut mine down and still see 20~30# an hour or more later, so you want to know if it drops right away or in a few minutes which would indicate some issue, at least.

Might be line leak or fuel pressure regulator if it does. You can pull the vacuum line off the regulator to check for raw fuel if you can get back in there to work.

Did you check codes? If you don't know how, let the local auto parts store check for you.

I've not checked codes - my understanding is you need a jumper wire and have to count dash light flashes?

Where would I mount a fuel pressure gauge on the rail - would it be at the relief valve (valve with a cap similar to a tire valve?

Thanks again

KMT
10-18-2014, 02:32 PM
I'd either ask a local store or hop to pull codes (usually for free), or invest +/-$30 in a code reader. Example: http://www.ebay.com/itm/Ford-OBD-1-Code-reader-Innova-3145-/181556330294?pt=LH_DefaultDomain_0&hash=item2a4599bf36

Fuel gauge on rail example: http://www.sccoa.com/forums/showthread.php?35944-Fuel-pressure-gauge&highlight=fuel+pressure+gauge