No Hot Start , found the problem ....

[onetinsoldier]

Once again the "no hot start" issue is a no fuel issue ! I have fuel to the rails , good pressure , good spark , but something is causing the injectors not to fire when its hot . I spray carb cleaner and it starts right up and runs fine . I don't have a scan tool to see what's going on, I have the service manual and I'm tired of reading ! I need an answer and someone has it !

New :
Crank sensor
coolant temp sensor
fuel pumps

[Marc Haibeck]

Is there a VATS lock out? The Security lamp should be off when the ignition key is in the crank position.

You should measure the fuel pressure with a gage. 10 psi of fuel pressure will spray out like crazy if the schrader valve is depressed. But the engine won't start with 10 psi. Normally there is 45 to 50 psi fuel pressure after the prime cycle.

The MAP sensor pressure must be over 20 kpa to fire. The voltage on pins A (black wire) and B (light green wire) must be over 1 volt to start.

[onetinsoldier]

I have a gauge on the fuel rail and it has about 55 lbs. I thought if vats was causing it, it would not let the starter spin ? is it possible to stop the injectors from working and not the starter ?

[Marc Haibeck]

If someone had a no crank condition in the past, the VATS starter control may have been disabled. Someone could have also removed the Security lamp. Does the Security lamp blink when the door is open? It should. It should go off when the door is closed. It should not come back on when the ignition key is turned to start.

[onetinsoldier]

Yes the security light blinks . If I spray carb cleaner in the plenum , it starts every time , so something is not getting the injectors to spray when the engine is hot and you park , then go back to start it to leave where ever you're at !

[-=Jeff=-]

What year?

Wonder if the Injectors are shorting when hot..

[Ccmano]

Originally Posted by onetinsoldier

Yes the security light blinks . If I spray carb cleaner in the plenum , it starts every time , so something is not getting the injectors to spray when the engine is hot and you park , then go back to start it to leave where ever you're at !

You say it starts when you spray carb cleaner. Does it keep running or simply die after a few seconds of running?
H

[A26B]

I don't see where you have measured the fuel pressure on each pump separately. When it is cold, both the primary & secondary pumps are activated. When the engine warms up, the secondary pump shuts off and remains off until the parameters are met for Secondary Port Throttle activation.

So, if your primary pump is bad, the engine will die when it gets warm. Likewise, it will not start when its hot because the primary pump is dead, i.e. the primary injectors will not spray/deliver fuel.

I am betting the gauge reading on the fuel rail with 55psi was probably taken with the key on, engine off and cold. The pressure reading is likely only from the secondary pump.

You need to verify the Primary Pump is either dead or alive. Do so by removing the fuse for the secondary fuel pump & check fuel pressure with key on engine off. If it is below 40 psig, replace it.

[onetinsoldier]

Ok , after having a couple of days off to test some things ….. after a test drive , it would crank but wouldn't start as usual . So I decided to put my mechanical fuel pressure gauge on , a rag collected the fuel . Got in the car it starts right up , I shut it off , tried starting it again , no start . So I bled the fuel rails to Zero pressure , and it started right up . So then I checked the return line to see if there was a blockage , there wasn't . That only left one thing ….Injector failure . Injectors were locking up under pressure.

I replaced all 16 and no more problem ! Starts when hot !

[Paul Workman]

Originally Posted by onetinsoldier

Ok , after having a couple of days off to test some things ….. after a test drive , it would crank but wouldn't start as usual . So I decided to put my mechanical fuel pressure gauge on , a rag collected the fuel . Got in the car it starts right up , I shut it off , tried starting it again , no start . So I bled the fuel rails to Zero pressure , and it started right up . So then I checked the return line to see if there was a blockage , there wasn't . That only left one thing ….Injector failure . Injectors were locking up under pressure.

I replaced all 16 and no more problem ! Starts when hot !

Well, THAT ONE is one to make a guy go, "Hmmmm...." Injectors (ALL) quit when engine is hot?? I hear what your saying....but methinks there's more to to be known on this one.