Help efi stalling

[BLUE72]

Here is a little background.
Bronco rebuilt about a year ago
New proformance 351w with mass flo efi.
new Mallory dist. and Mallory coil
New painless wiring
New BC tank with fuel accumulator.
Everything on my bronco is less than a year old. The only thing I have had to fix since the build was a bad starter just before I put it away for winter.
I just started having this problem after I broke it out from winter storage. .
After about 15 min. of driving it will stall. It does not sputter or anything like that it just kills the motor. If I wait about an hour it will fire right back up run great and then after about 15 min. it does the same thing.
When it stops running i still have power and everything will work. Starter will crank I can hear the fuel pump and I have 40 pds of fuel pressure but it will not fire for about an hour. So far I have replaced the following
New MSD coil
New TFI module (grey version) original was black
Still having the same problems
Any help would be greatly appreciated.

 

[bax]

Next time it stalls take some gas and put it down the intake. Then crank it. See if it starts. Does it have a surge at idle? If it starts and then dies again you have a fuel issue. You may need to richen up or adjust your pulse width. can you do that with a mass flow system?

 

[BLUE72]

No surge at idle. My fuel pressure gauge is mounted just before the fuel rails and always reads 40pds. The mass flo system does not have any adjustments. It is suppose to be a plug and learn system. Is it ok to dump fuel down the intake of an efi system.

 

[BLUE72]

I kind of think it is a spark issue. The reason I replaced the coil first was after it stalled the first time I put my tester on it and it was not putting anything out. I put the new MSD coil on tested it worked great fired it up drove for about 15 min. Bronco died and then no juice coming from the coil until the motor sits for about an hour so then I decided it was the TIF module. Thanks for the reply Bax.

 

[NY-Bronco]

Check for vacuum leaks. I had an issue 3 weeks ago with my rig stalling and running like crap. Turns out some hoses came loose.

 

[BLUE72]

No vacum leaks. Plus when it starts after it has set, it fire on the first crank and run great for about 15 min.

 

[bax]

You can put gas down an EFI intake no problems. That is why I wanted you to do it. if it is a spark problem it will still not start with the extra gas. but if it is a fuel problem it will fire with the new gas in the intake. I am trying to eliminate half the system to figure out what to check next. You have a TFI module is it a direct mount or a remote mount. If it is a direct mount you should change it to a remote mount and get it off the distributor. The distributor is one of the hottest spots on an engine, except the exhaust. When TFI modules get hot they stop working. When they cool they sometimes work again and sometimes don't. Do you have a spark box? is it mallory and digital? Digital is the only way to go. RF noise will f with your computer. A digital spark box is very clean RF wise.

 

[BLUE72]

Bax
I will try the gas in the intake here in a few. My TFI is a direct mount. I just read up on what a disaster that thing is. I just put a new one on but the weird thing is our temps are very low for this time of year 60s-70s and all last summer we had temps in the 90s and it ran no problems engine temp was usually 190-200. Right now I can't get my temps about 170. Any suggestions on were I can pick up a remote mount. I do not have a spark box on it.

 

[bax]

Junkyard. Ford made a nice heat sink to mount them on. I remote mounted mine and it made a big difference. I don't care how hot is is outside. it's hot on that distributor. I got a picture here somewhere.

 

[bax]

http://classicbroncos.com/forums/showthread.php?t=148561&highlight=remote+mount+TFI

 

[buckenbronco]

will it start up instantly? or do you have to let it sit for a few?

 

[jw0747]

if you disconnected the battery during winter ECU memory might need to be reset. instructions on how to reset are in Part 3 below. also has helpful steps when idle is lousy.
resetting ECU memory cured my no idle problem after Bronco sat in body shop for awhile with battery disconnected.

http://www.muscularmustangs.com/iac.php

 

[rustbucket]

Something is heating up and expanding causing a gap somewhere. Check the cap and rotor. Check all wires to the coil. You could have another bad coil, too.

 

[NYLES]

got a spare ecu?

 

[75junebug]

I had the same issue, and could not find what was wrong. I bought new TFI, New pu coil, new distributor, checked all connections etc..... i finally started ripping it all out to re-install my SINGLE wire HEI dizzy, and Q jet car when I came across the relay next to the ECU under the dash. It had signs of water damage, and was prolly causing all the issues.
Unplug all relays and check for burned contacts or signs of moisture

 

[ransil]

How did you wire pin 30 of the NSS ??

see here:
http://classicbroncos.com/forums/showthread.php?t=172541

no hot start is one of the symptoms of a burnt computer trace from wiring pin 30 wrong, not sure about Hot stall..

Did you pull codes??

 

[crews44]

ransil...you beat me too it......

 

[patkelley]

I had this same problem in a 351W mustang track car. We found 2 possible issues - fixing both solved the problem, so I am not totally sure if it was one or the other....
1) remote TFI mount like Bax depicted - it seems that the 351W has issues with TFI heat related failures like you're describing.
2) wiring harness to the fuel pump - the OEM Ford connector for the fuel pump Fox body Mustang failed. I assume that you have an aftermarket solution for your fuel pump wiring, but if you are using OE Ford connectors for the fuel pump (in the mustang they were at the back of the gas tank, behind the bumper), you may want to check them.

Good luck