Intermittent starting issues...

[MDK210]

I had a return sytle fuel system installed a couple of months ago then two days later I moved from VA to CO so I never drove it. Car ran like balls when I got here so I had it retuned last week. Car ran great so I took it home and the next day I drove it for about a hour then kept it in my heated garage for the night like always. Went to start it the next morning and she would just keep cranking but not starting. Had it towed to the performance shop and 40min later they called and said it started up fine! They held onto it for a few hours, raised the spark some in the tune and started it 15-20 times they said and no issues or codes thrown. I left it there overnight and picked it up the next day with no problems starting it, drove it home a hr and ran great then let it sit overnight. Woke up today and the same damn thing!

Car runs great when it runs so I don't think it's the tune and the battery is new. I pulled a plug, she sparks fine and there's no abnormal discoloration and I can smell fuel on the plug. What the hell could be the problem? Every time I tow it in it cost me $100 and the only thing I can tell that's different is that it was warm out on the 40min tow and it was sitting in the sun while there. Could I seriously be blaming the sun on why it won't start, lol. I had a compression test ran a few weeks before the system was installed and compression was good, I can hear the dual pumps coming on and fuel flowing so WTF else can a normal person like me can check?

 

[sur_real1]

Could you be vapor locking?

 

[MDK210]

Could you be vapor locking?

I thought that was more common with older vehicles? Granted I have a return style system but I don't know enough about vapor lock. I have braided lines and a reputable kit with Aeromotive products and have never heard any issues with this style of system so far.

 

[sur_real1]

I thought that was more common with older vehicles? Granted I have a return style system but I don't know enough about vapor lock. I have braided lines and a reputable kit with Aeromotive products and have never heard any issues with this style of system so far.

Well, maybe worth a try and removing your gas cap and letting it sit for a little while before starting the next time this happens.

Best of luck!

 

[MDK210]

what does removing the gas cap do?

 

[sur_real1]

If I remember right, it releases any vapor like fuel from the system out of the tank. Granted this was usually a problem on older vehicles with a mechanical pump. But if there is a problem with your fuel system, this might bring that to light. Do you have a fuel pressure guage?

 

[MDK210]

If I remember right, it releases any vapor like fuel from the system out of the tank. Granted this was usually a problem on older vehicles with a mechanical pump. But if there is a problem with your fuel system, this might bring that to light. Do you have a fuel pressure guage?

just tried it, it tried harder than it normally does but still wouldn't start.

Yeah I have a FP gauge.

 

[sur_real1]

So, a couple of things:

- I think when you remove the gas cap on these cars there is a check valve that keeps gas from sloshing out when filling. Hold that down for about 30 seconds as this can help keep things in.

- Check your fuel pressure at the check valve on the fuel rail to make sure you have optimal fuel pressure for your setup... I don't know what your fuel pressure would be with this new system.

- One other option is it could be a short somewhere. I would check the harness going to the fuel cutoff switch in the trunk to start. You might also have something funny happening with the computer. When you place the gas pedal to the floor, it cuts fuel to the engine to keep someone from trying to start the car like an old caddy with a carb. This system might be malfunctioning.

So many possibilities on these damned cars as I've had to crawl all over the wiring harness recently with the uber large ford manual.

 

[MDK210]

well the guys that normally tow my vehicle to the performance shop are also mechanics and begged me to leave it with them. They said the fuel pressure was too high (40psi) and it was basically flooding the engine when I would try and start it. They adjusted it and it starts now but the real test will be tomorrow when they try and start it cold.

I called the performance guys back to see if I needed a re-tune and they said if my base fuel pressure was adjusted then yes. BALLS!

Does this make sense to anyone?

 

[MDK210]

after taking it back to the tuners they took off the vacuum line, adjusted it back to 39psi, re-attached the line and kept it for a few days. They said it hiccuped once but never didn't start. When it did have a issue, they turned it off immediately and floored the gas pedal to cut off the injectors and started it with the fuel already in the cylinders from the previous crank. I've had it for two days and it seems to work fine again so who knows what the issue is/was. We're thinking that since the fuel lines are so massive along with the dual Walbro pumps, 42lb injectors and the rest of the fuel system that she's susceptible to easier flooding since a turn of the key sends a massive amount of fuel compared to the stock system at this pressure. Maybe a long stretch or we're lying to ourselves but we don't have anything else to grab on to, ha. Either way so far so good.