No start condition

CHP 3705 · #1 01-12-2008, 08:04 PM

I've been working on my 88 CHP the last 2 1/2 weeks trying to get it back together so I can drive it in and out of the shop instead of pushing it. Keep in mind this was a damaged rolling shell so I had to replace everything that was gone. I finally got it together last nite and tried to start it. Wouldn't start. I shot some gas into the intake, still nothing. I replaced the ignition module and it started right up. This morning I went to start it, wouldn't start again. I shot some gas into the intake, took right off. To make a long story short, this thing won't start unless you prime it first. Anyone have any idea what is wrong with this thing? I've been working on these Fox Mustangs for 25 years and I've never had one do this. Doug

ImEvil1 · #2 01-12-2008, 08:24 PM

Doug,

Do you think it's a fuel pressure issure? I had problems with the wife's car...progressively hard starting that worsened with time, and it was running rough. I thought it was the fuel pressure regulator, or a stuck injector, but she took it to a local shop that we trust and they couldn't figure it out. Turns out it was the FPR.

fajr22 · #3 01-13-2008, 01:13 AM

If I had to guess I would say the pcm is not turning on the 3 sec prime to the fuel pump. This is controlled by the distributor. the pickup coil sends signal through the module to the to the pcm relay which in turn grounds the fuel relay for 3 sec prime until it sees rpms, I would say you are not getting this. Make sure the distributor is tight, otherwise it will not ground and turn on either relay. Meaning if it is loose in the block it may not ground. My suspect would be a bad pickup coil in the distributor, because this, not the E-coil is what usually kills the TFI module. First I would test the fuel pump relay for the prime signal, it is a green housed relay next to the brown pcm relay. These relays, are either next to the PCM or under the drivers seat I believe. I would check for a prime signal and power there and if present i would either replace the relay or take the cover off the relay and manually engage it. if the pump fires and the car starts, and If all the variables are there then I would say you have a bad realay. If there is no prime signal I would head to the distributor where you have already been. Like i said earlier make sure that the distributor is tight if it is not then the TFI and the pickup may not be getting the ground they need to make things happen. Otherwise i would bet on the pickup in the distributor. Let me know if I can help on anything.....

FRED ASHMORE

86NeSSP · #4 01-14-2008, 12:34 PM

When you turn the key to the run position do you here the fuel pump kick on? If not it could be a fuel pump, the relay for the fuel pump or the PCM.

Make sure to check that all the gorunds are good.

Good luck,
Matt

CHP 3705 · #5 01-15-2008, 06:11 PM

I replaced the relays, distributor, & processor with known good parts & still the same, won't start unless you shoot some gas into the intake. The relays are working, you can here them click. Fuel pump works fine. It just won't start on it's own. It's got me stumped. Doug

86NeSSP · #6 01-15-2008, 06:35 PM

Quote:

Originally Posted by CHP 3705

I replaced the relays, distributor, & processor with known good parts & still the same, won't start unless you shoot some gas into the intake. The relays are working, you can here them click. Fuel pump works fine. It just won't start on it's own. It's got me stumped. Doug

Have you made sure the fuel pump cut off is good? can you bypass it and check to see if you are getting power back there?

Matt

fajr22 · #7 01-15-2008, 10:52 PM

Try slight throttle and see if it starts?? if it does then that means it needs a tps. A tps will shut off the injectors at cranking if it is out of range. Then when you prime it or give partial throttle it changes the range and allows them to fire. I have had this happen before as well. keep posting and I'll keep trying to get it fixed. The one thing i hate about ford diagnostics is you cant display the data before 96....

good luck FRED ASHMORE

CHP 3705 · #8 01-16-2008, 01:26 PM

Quote:

Originally Posted by fajr22

Try slight throttle and see if it starts?? if it does then that means it needs a tps. A tps will shut off the injectors at cranking if it is out of range. Then when you prime it or give partial throttle it changes the range and allows them to fire. I have had this happen before as well. keep posting and I'll keep trying to get it fixed. The one thing i hate about ford diagnostics is you cant display the data before 96....

good luck FRED ASHMORE

BINGO!!!!! I had tried partial throttle before without any luck, but since this car sat for a long time without a hood on I thought I would just change the tps. Started right up. Ran great. I restarted it a couple more times but it idles @2000 rpms. It did that a couple times before I changed the tps tho. I had an 87 LX that did that years ago and I was told it was the ACT sensor, so I changed that and it was fine. That's the next thing I will change on this one. THANK YOU FRED. Doug

NoDrama43 · #9 01-16-2008, 02:42 PM

Fred,

excellent tip.....thanks for helping out !!

86NeSSP · #10 01-16-2008, 03:09 PM

Great Tech Fred... Glad you got it running Doug!

Matt