Possible Stuck Open Intake Valve and No Apparent Local Expertise....

[ormgott]

Got an "86 F250 last year with 7.3 swap that ran fine for about 2 weeks. After that, no start. Replaced lift and injection pumps. Both are working as expected. ALL standard startup checks (prime, starter rpm, etc) were tried. Symptoms are no start and fuel vapor coming up through the intake and also out exhaust. I'm so busy with other projects that I can't work on it, but it seems like if the vapor is coming back through a stuck open intake valve it could cause too rich a mix to fire the other cylinders? Also, I'm located in Connecticut somewhat southeast of Hartford and haven't been able to find a shop that doesn't immediately say "Oh yeah, that'll be $3000+". Add to that the fact that I seem to know more about it than they do (and I'm pretty much a newbie!) Anybody have ideas?

 

[The_Josh_Bear]

First thing is to pull the fuel filter off after it's been sitting and see if it's full or not. If not, you have air intrusion and need to turn over the engine while depressing the schraeder valve to purge air.

So when you crack the injector lines at the injectors(as many as you can reach without struggle), and then crank over the engine, you're getting a squirt of fuel from each one? If not the IP isn't doing its job.

If yes then it could be glow plugs not doing thier job. You can plug in the block heater for 3 hours or use a sniff of ether, but do not spray the ether until the engine is already turning!

Even if an intake valve was hanging open the engine would still run. So if we can get it running then it would be easier to figure out if the issue is still present or not. Although fuel vapor out the intake doesn't sound good.

 

[Isaac Ristow]

What you see in the intake is probably just blowby from the CDR port. Josh's reply is a good start for what you should be doing

 

[ormgott]

Thanks for the quick responses. All pumps involved are working correctly and flow to injectors has been repeatedly checked both by me and others who thought I hadn't done it correctly ;-) Have used block heater & checked glow plugs, used ether (no attempt to fire even with that). CDR port is from crankcase, correct? Do need to check that possibility, but would that shut the engine down?

 

[CDX825]

Doubt very seriously an intake valve it stuck open. These are interference engines so the piston would be hitting the valve if it was stuck open.

If your glow plug system is questionable try plugging in the block heater for a couple hours and then try starting it.

 

[IDIBRONCO]

Have you tried cracking all 8 injector lines at the injectors? Sometimes air can be very stubborn and refuse to bleed out with a closed injector line. I don't believe that a bad CDR will cause an engine to quit running and not start up again.

 

[The_Josh_Bear]

Do you by chance have manual transmission?

If so, have a friend buddy-tow your truck around in 2nd or 3rd gear until it starts. If you have fuel going in the cylinders it WILL start.

 

[Big Bart]

Something other things to check. You say it just died and you have not been able to even prime.

1) Try blowing air from the rubber line going to the lift pump from the fuel tanks. Not 150 psi from your compressor more like 10psi. Before you do, take the gas cap off. Then listen for bubbles and air. Long story short there are a lot of things including, the transfer valve, a bad fuel sending unit (Out of diesel.), broken pick up, tank debris, air leak, etc. that could be in play. You need to confirm good fuel availability. Some run a fuel line from a 5 gallon can of diesel to the lift pump to test And confirm they do not have a fuel delivery problem.

2) Check for 12v+ power at the IP solenoid with the key in the on position. It’s inside/on the top of your IP. No power no start. If you have power connect and disconnect the power a couple times, you should hear a quick click on or off As it moves. Bad soleniod = no start.

3) Although not on this site, several IDI owners have told me that a bad IP caused the truck to just die and not restart. Although not common keep that in mind. Most hear found the truck would only start when cold.

4) Keep a battery charger hooked up and turned on, you might be surprised how a little faster cranking goes a long way with a diesel.

Some struggle to get their IDI primed again, check out the above, try to prime a couple more times. Don’t give up you will figure it out.

These trucks are old so often multiple issues are at play. As mentioned above try bump starting if you have a stick shift and a second truck.