Grandson 1991 Ranger 3.0 v6 69,000 miles We have a long start issue after it has sat for 30 mins. plus. If you open the throttle part way while cranking it will start fairly easily. Fuel pressure comes up instantly when you turn on the key. It runs at 39 psi pull the vac line off regulator it jumps to 49 psi. Fuel pressure does drop to about 30 psi after setting an hour. It kinda acts like it is flooded when it starts. so far we have done a complete tune up plugs wires cap and rotor. The ignition module has been replaced twice last one a real Motorcraft. New fuel pump and filter. Cleaned the fuel injectors with Ford cleaning system . Kinda running out of ideas. I will replace the coil next and maybe clean the iac. Any ideas would be appreciated.

 

Boy you've been busy on this one. With all of the things you've done, checking the usual suspects, it kinda sounds like a fuel injector with a runny nose, as you've noticed it acts like an over rich fuel condition on a restart & the psi leaks down in an hour. When you replaced the plugs, did you do a cyl plug read as you removed them???? Do you remember Any particular cyl spark plug looking more carbon fouled than the others???? If so, maybe pull that cyl fuel injector for inspection & or bench testing.

Any trouble codes set, or pending???? Did the problem come about suddenly after some event, or slowly over time????

More thoughts for consideration, let us know what you find.

 

Well i did a leak down test on the fuel rail only. Nothing jump out there held 90 psi for an hour. So i replaced the Fuel pump with a a new Bosh (man they are quite) thought I had fixed it. No such luck. Only codes are an 11 and 10 which means all is well checked the timing it is right on the money test the IAC it seems ro be working fine. My old sun analyzer says all the plugs are firing normally and it idles like a top. and will start right up if it doesn't set more than 30 mins. anything after that and you need to open the throttle to get it to start. No fuel in he FPR vacuum line. There is no egr on this truck. But what is the sensor on the intake just behind the egr block off plate.

 

OK, well lets think about this some more. It takes air, fuel, spark & compression to make em run, so what's going missing when it won't start after an hours hot shut down heat soak?????

Seeing as it'll start if you open the throttle a little, it sure sounds like its a fuel delivery problem of some sort.

SO, is the fuel old, such that it might be winter adjusted for a lower vapor pressure???? If so, it could be vapor locking after a hot shut down heat soak.

I've also heard of coilpacks & icm's offering up trouble with a wimpy spark after a heat soak.

Is the battery voltage up to snuff after a hot engine shut down heat soak???? Monitor it while your helper cranks the engine.

I have the code 10 as cyl 1 low on cyl balance test. So does cyl 1 have a compression problem????

Did the problem come about suddenly, after some event, or slowly over time????

 

Fuel is new. Havent owned truck very long. When i bought it it had an occasional miss that was a bad wire. Did complete tune up. then fuel pump quit replaced with one I had here at the house also installed new filter. Then Ignition module quit replaced that. Never have caught it with out spark using a spark tester. Replaced fuel pump with new Bosh unit it honestly acts lack it is losing fuel prime. Fuel rail pressure test didn't showed negligible pressure loss over an hour. I should have checked the pick up tube for a crack will do that next.

 

If you think its a fuel pressure bleeding off, next time it doesn't want to hot start, cycle the ignition switch from off to run 3-4 times, remaining each time at "on", long enough for the fuel pump to run for a couple of seconds & time out, Then go to start to crank the engine & see if it makes a difference in how it starts.

Are you certain the TPS resistance is within range when its hot & the throttle is closed???

 

Here is an update i installed new fuel injectors and put on a new motorcraft TPS. And I still have the problem. It runs good has good power cruises nice down the road. Starts fine cold. Starts fine after setting ten mins. Long hard start after 30 mins have to open throttle to get it to start. Here is the list of what has been done.
New Bosch fuel pump and filter.
New cap, rotor, wires and plugs. Timing is spot on.
New FPR
New set fuel injectors
New TPS
New ICM
New coil
checked wiring harness connectors for corrosion
checked for vacuum leaks

Fuel pressure normal and doesn't leak off over a period of an hour.
plenty of fire from coil. When it does the long start it acts flooded
P.S. No codes

Anybody got any ideas. Only thing I can think of now is the distributor

HELP

 

Still chasing this problem contemplating changing distributor. Here is a picture of the hall effect pattern as seen from my very old Sun machine's o-scope. This is a ccd system. Does any one see any thing wrong with this. I really don't have any thing to compare it to.

 

 

Hall effect photo isn't up. WOOOOPS it just popped up as I posted this. Nice square wave, looks ok to me.

 

In post #3 you said that the fuel rail was at 90 psi, that's way over spec. With it leaking down to 30 psi in an hour, it suggests something has a runny nose.

 

I tested it at 90 psi. It runs at perfectly normal pressures. It can set over night and it will start perfectly. the only time it long starts is after a 20-30 min shut down after it has been brought to temp.

 

Ok at what conditions did you test it at 90 psi???? The hard start after a heat soak & you having to give it some open throttle to start is a clue.
As noted in post #4, its usually a spark, or fuel problem. Fuel can be from low vapor pressure winter fuel boiling after a heat soak & creating a vapor lock condition, to an over pressure condition causing an injector runny nose. To a heat soak causing a coil, or icm electrical problem.
Seeing as how you've measured 90 psi at some point, it would be helpful to know under what conditions that 90 psi over pressure was measured.

 

I set the 90 psi pressure with my fuel injection cleaner. The fuel pressure is normal with truck running.

 

OK, I understand now. You set the 90 psi at the fuel rail with your injector cleaning system, to check for pressure bleed down over time.
SO, it seems we are left looking at a hot soak problem, question is if its fuel, or spark related. So, have you checked fuel pressure when its hot & hard to start & checked spark quality under the same hot conditions????