Started great - now takes cranking...

[BigRedWeather]

All winter my truck has started within 1 second of turning the key after I fired the glow plugs. Ten days ago, after no changes had been made, and no change in the weather I would have to turn the key on about eight times, from 3 seconds to 1 second, glowing a few more times in between and all of a sudden it would catch and start like it used to. Catch = sounded like it got fuel and would turn over under its own power instead of the starter's power.

I put a new fuel filter in and verified that I have a good supply of diesel to the top of the engine. I was hoping that for the first minute or two the diesel pump wasn't supplying fuel to the engine, and then started doing its job, because this is what appeared to be happening, but diesel is being supplied to the top of the engine at good supply and pressure.

For 15 seconds after it starts sometimes I have to hit the pedal a little to smooth it out, but after that it runs like a top, with all the power I expect.

Possibly air in they system somewhere? If so, how do I get rid of it?


Thanks,


BigRedWeather

 

[Kalashnikov]

Sounds like glow plugs not fuel. I would test resistance on the plugs first and check the relay if the plugx check out. Then I'd double check for leaks all around the top end IP/lines, filter, lift pump, and fuel selector valve/tank lines.

 

[Mike]

I'm betting on the GPR. Take a heavy screwdriver and jump the two big terminals for 30-45 seconds and then try to start it.

 

[79jasper]

Then I'd double check for leaks all around the top end IP/lines, filter, lift pump, and fuel selector valve/tank lines.

We don't have IP's though. Our lift pump is in the valley, it sits almost under the turbo.
As I understand it, it's a dual action pump with a high psi side and a low psi side.

I would start simple by: testing the relay, testing the glowplugs, testing the UVCH.
If the relay is suspect, get the stancor.

I can't remember which exact years, but some had a problem with the HPOP losing it's oil because of a anti-drain back valve.
Might be 94 blocks.

Another thing I've learned is to not trust the WTS light. Mine would randomly stop so I thought my glowplugs weren't working, but in reality it was just the bulb connection.

 

[Kalashnikov]

Shiiit, I thought I was in the IDI section. In that case I'd go with glow plugs. My PSD will just crank and crank and sounds like it wants to start when not plugged in with cold weather. Fires right up when plugged in and given a little throttle to smooth out.

 

[BigRedWeather]

Learned something today. When I was in the middle of turning the key to start several times I noticed smoke. Popped the hood - it was coming from the Back Pressure Control Valve. I couldn't tell what position it was in but I'll bet it was closed. (It was 50F) I would also assume that after cranking for a while, it opened, and then it fired right up. Tonight I grabbed it and was able to move the valve some by hand. Perhaps the BPCV Selenoid isn't working properly.

Can some one describe the proper function of the BPCV on start up in 50F weather and much colder?

Can some one describe the proper function of the BPCV on start up in 20F weather?

I have another turbo with ~200k on it. Could I swap out the BPCV Selenoid? It is a very different job but compare this job to say swapping out a transmission. Is this harder or easier? Any special tools?

Or is the problem something else?


Thanks,


BigRedWeather

 

[79jasper]

Well the EBPV should be opened during cranking. It's closed by oil pressure. It shouldn't close until the engine has been running for 30 seconds.

You will need new turbo pedestal o-rings.

You will find a EBP sensor right behind the HPOP. It connects to a metal tube that runs to the passenger exhaust manifold. The tube itself becomes clogged with soot, and causes wacky things.

 

[BigRedWeather]

I see guys are getting rid of the EBPV function by:
1) disconnecting the wiring
2) disconnecting the link between the solenoid and the valve.

I really need the quick heat up, but I also need it to start reliably.


BigRedWeather

 

[79jasper]

I would say it sounds like the solenoid/actuator part is shot. Check to see if it's leaking oil around the actuator arm on the pedestal.

I had thought about deleting mine, but decided I would rather have it as an exhaust brake.

 

[Mike]

I see guys are getting rid of the EBPV function by:
1) disconnecting the wiring
2) disconnecting the link between the solenoid and the valve.

I really need the quick heat up, but I also need it to start reliably.
BigRedWeather

Hmmm, I live in a much much colder climate than you do and I gutted my EBPV and never once missed it.

 

[7.3 man]

The back pressure control valve you were talking about you wouldn't be able to take some wire and tie it open and wait for a cold day and try it so you know that's what it is?

 

[79jasper]

The back pressure control valve you were talking about you wouldn't be able to take some wire and tie it open and wait for a cold day and try it so you know that's what it is?

That could be done. Just make sure it's unplugged first.

 

[BigRedWeather]

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