Newb Questions

[vt951]

Just get up under the hood there and crack open a couple injection lines at a time and have someone hold the throttle to the floor and crank the engine over while holding the pedal down. Once fuel is coming out good, tighten those 2 and do two more.

You can also hold the throttle open yourself under the hood and cross the solenoid with wrench of something, just make sure the key is on so that fuel is flowing. Just be safe and be ready to pull the wire off of the fuel shutoff solenoid if anything goes wrong.

I just bled all 8 like you said, and it still won't turn over. Oh well. When I get back from vacation, I should have a Hoffman compression tester waiting for me, so we'll see if it something major or not.

 

[vt951]

Also I had a problem w/ the fuel seperator located near steering stem on fire wall. After trying everything you have discussed several times till I was about to choke someone, It came to me in my sleep to by pass the water seperator.(real easy to do) The stupid thing was plugged and would not allow any fuel to get to pump. The more I cranked, the more air I kept feeding the system. This may be way off from your problem but may save you problems down the road.(Mostly if you live where its cold)

If I'm getting fuel at the inlet to the injection pump and at the injector lines, then the water seperator shouldn't be the problem, right?

 

[troutwest66]

After the filter separator you should be getting about 7 PSI if I remember right. On the 7.3 there is a schrader valve on the filter head where it can be checked. I don't know about the 6.9. Maybe the lift pump isn't supplying enough pressure.

 

[towcat]

If I'm getting fuel at the inlet to the injection pump and at the injector lines, then the water seperator shouldn't be the problem, right?

you're right. but do keep in mind, the firewall mounted water seperator is a problematic area for the earlier trucks.

 

[vt951]

After the filter separator you should be getting about 7 PSI if I remember right. On the 7.3 there is a schrader valve on the filter head where it can be checked. I don't know about the 6.9. Maybe the lift pump isn't supplying enough pressure.

There is a schrader valve on my filter head. I screwed on a fuel pressure gauge, and it doesn't get any pressure. I'm not sure what's going on there, like maybe the gauge doesn't fit right, or the schrader valve is bad? Or, maybe, like you said, the lift pump might not be supplying enough pressure.

I think my plan of attack now is:
1. check the cylinder compression, and if reasonably good...
2. pull the injectors and get them tested, and if reasonably good...
3. replace the fuel pump

 

[91f2504x4]

There is a schrader valve on my filter head. I screwed on a fuel pressure gauge, and it doesn't get any pressure. I'm not sure what's going on there, like maybe the gauge doesn't fit right, or the schrader valve is bad? Or, maybe, like you said, the lift pump might not be supplying enough pressure.

I think my plan of attack now is:
1. check the cylinder compression, and if reasonably good...
2. pull the injectors and get them tested, and if reasonably good...
3. replace the fuel pump

When you bleed all 8 injectors I am assuming you had a good flow of fuel coming from each one. Did you see any smoke from the exhaust then? Have you had someone crank the engine over while you push in on the schrader valve to see how much fuel comes out. I had a similar problem withmy truck when the stupid pickup I made for the fuel tank was a bit too long and even though I cut a V in it, it was still sucking to the bottom of the tank and wouldn't let me holley pull much fuel.

 

[icanfixall]

When you installed the fuel pressure gauge did you remove the valve in the schradder valve. If the core stayed in then you wont "see" any pressure...

 

[vt951]

When you installed the fuel pressure gauge did you remove the valve in the schradder valve. If the core stayed in then you wont "see" any pressure...

No, I didn't. I thought the fitting on the gauge would take care of pressing that in.

 

[vt951]

Well, I'm back from vacation, so I am working ******* the truck today.

First, I confirmed with absolute certainty that NO smoke whatsoever is coming out of the tail pipe during cranking.

I also did 2 compression tests and got these numbers:

Cyl----Test 1---Test 2
#1-----210------250
#2-----230------140
#3-----190------120
#4-----370------320
#5-----220------150
#6-----220------150
#7-----250------220
#8-----170------160

How bad are these numbers? Would this explain the no start problem?

 

[towcat]

min compression is 300 or no start.
enlist local OB help before condemning the motor.
we have taken it as far as we can online.
pm "diesel dog catcher" and see how far away he lives. he might be availible for road service if the price is right.

 

[vt951]

Also, I heard from someone that one cause of no-start problems on these trucks is lack of oil pressure? The guy said there is a sensor near the front of the air intake and if it isn't seeing enough oil pressure then it won't let it start (I guess it must cut fuel). Is there any truth to this?

 

[towcat]

Also, I heard from someone that one cause of no-start problems on these trucks is lack of oil pressure? The guy said there is a sensor near the front of the air intake and if it isn't seeing enough oil pressure then it won't let it start (I guess it must cut fuel). Is there any truth to this?

you've been talking to a guy who works on PSD's.
our IDI's need oil pressure but not as critical as a PSD.

 

[vt951]

min compression is 300 or no start.
enlist local OB help before condemning the motor.
we have taken it as far as we can online.
pm "diesel dog catcher" and see how far away he lives. he might be availible for road service if the price is right.

Damn that sucks. I'll pm him. Thanks, Calvin.

 

[vt951]

I guess I should add that this is on a cold engine (of course). I have read on here that you typically see lower numbers when the engine is cold.

 

[towcat]

not that low.