5.0 Slow to start.... sometimes

Ok, I picked up the XP8 back in February and slowly been fixing issues that I find.

One thing that is puzzling to me is a "slow to start" issue. The starter is new and spins over nicely, but sometimes the car does not "fire" right up. It will take 3-6 seconds or so of spinning before it "catches".

The only consistent time it will fire right up is first thing in the morning after sitting all night. (Doesn't matter if there is snow on the ground or 80 degrees - it will fire right up)

The previous owner said he replaced the fuel pump and tank. The tank does appear to be new. I replaced the fuel filter as soon as I got it.

The truck runs great, idles, etc. so there are no driveability issues, just this nagging "slow start"

Next up is new plugs, and maybe wires?

Any other ideas?

Thanks,

mine does this too... its not the supercharged xp8 but still.. what is your battery rated at (cca) cold cranking amps?.. your battery might not be sufficient enough..
pics of your ride!?

pbnj22 said:

mine does this too... its not the supercharged xp8 but still.. what is your battery rated at (cca) cold cranking amps?.. your battery might not be sufficient enough..
pics of your ride!?

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It's a Walmart special that the previous owner put in there - 650 CCA.

I don't think that's it though since the starter is spinning fast. My guesses are fuel pressure or spark?

There are alot of pics here, the previous owner didn't take very good care of it.. but it has all options but the brakes - http://s109.photobucket.com/user/ts_project89/library/Saleen XP8?sort=3&page=1

That is a little low.. i think spec is 675 to like 800 or something like that.. plugs and wires would certainly help.. use the right kind.. motorcraft basically everything else seams to run like crap.. change fuel filter might help... new air filter you can rent a fuel pressure test kit from autozone for free and test pressure.. i had to do that. there is a tutorial on here somewhere with how to do that..

could try cleaning IAC valve as well..

Have you noticed this happens more after you have ran it for a while turned off, then started back up after some time 1-2 hours?

If so then its the same issue i have and its the Fuel pressure regulator and if its a 99-2000 then the part is no longer made. You can get a replacement from a junk yard or jerry rig a fix with a locking plyers and a nut to stop the hoses.

Millertime1987 said:

Have you noticed this happens more after you have ran it for a while turned off, then started back up after some time 1-2 hours?

If so then its the same issue i have and its the Fuel pressure regulator and if its a 99-2000 then the part is no longer made. You can get a replacement from a junk yard or jerry rig a fix with a locking plyers and a nut to stop the hoses.

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Sounds about right. The only time it starts perfect is after sitting for 6+ hrs

Can you give more details on your fix? I'm curious.

Hmmm... we've had some unseasonably cool weather lately here in Indy, and the XP seems to be starting better.

As long as the engine is cool or hasn't been started in a while, say at least 6 hrs... it seems to start better?

I had the same with mine Limited V8, and it was the fuel pressure regulator. Another symptom was the fuel consumption a lot higher than normal, and also had some back fires that made the engine spit the vacuum hoses from the engine head.

swerneck said:

I had the same with mine Limited V8, and it was the fuel pressure regulator. Another symptom was the fuel consumption a lot higher than normal, and also had some back fires that made the engine spit the vacuum hoses from the engine head.

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Fuel pressure regulator on the fuel pump assembly? Or Fuel pressure damper on the fuel rail?

Thanks

It's the Fuel pressure damper on the fuel rail, but my mechanic was calling it fuel pressure regulator. Anyway, it's on the fuel rail, at the end.

swerneck said:

It's the Fuel pressure damper on the fuel rail, but my mechanic was calling it fuel pressure regulator. Anyway, it's on the fuel rail, at the end.

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Cool, thanks for the input.

I have the same problem, starts up just fine if its been sitting for a long time, or restarted immediately. Slow to catch if its been sitting for a few hours.

Nice truck! A little rough, but still given the low miles it's a nice truck.

I haven't been able to fix the issue at all. It's more of an annoyance then anything else.

Millertime1987 said:

I haven't been able to fix the issue at all. It's more of an annoyance then anything else.

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What test have you ran ???

Well the shop i would go through has tried other parts from junk yards and parts they got from stores.
The manager of the shop was able to get a fix on his mountaineer to bypass the dampener but i havn't gotten it done. I can let you know i may try to get it done this weekend along with the swaybar links.

Well, here's an update -

I found a '99 fuel rail with damper on ebay for $40, swapped in the damper from the ebay purchase and it appears to have fixed the problem.

I started it twice - lunchtime and after work - both about 4 hrs or so from the time I shut it off. This scenario always was a slow start condition.

I'll keep my fingers crossed and my eye out for a new part, but it appears to be obsolete. Part # is XL2Z9F775AB if anyone knows of an obsolete parts house.

Rockauto carries them in stock. They list it under fuel injection pressure regulator. New costs from $30. Motorcraft is $52. There are discount codes for them on the forum.

Did you ever test the fuel pressure?

RomeovilleIL said:

Rockauto carries them in stock. They list it under fuel injection pressure regulator. New costs from $30. Motorcraft is $52. There are discount codes for them on the forum.

Did you ever test the fuel pressure?

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I'd love to see a screen shot of where you're seeing it because it doesn't list it under a '99.

You can buy the regulator all day for a 96-98, but the '99 up used a damper. It's physically different. The regulator for a 96-98 bolts on (like a mustang), but the '99 damper is held in with a retaining clip.

Nope, never checked the fuel pressure.