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My 7.3 prefers a 80wmo/20k1 blend. Below 70* the engine hesitates. I hope my bigger fuel filter mod works. It has about twice the filtering media. I'm already getting 1psi more fuel pressure.

Have you checked your fuel pressure between a 70* day and a 100* day?
 

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Discussion Starter #22
No I haven't. I've got all dummy gauges. Might be a good idea to put a gauge in and check it out.
 

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Blind DrIver-which size of fuel line is?
 

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Discussion Starter #24
I had a thought today and checked my Cold Timing advance solenoid and High Idle solenoid. Both are non-functional. The throttle adjustment is also adjusted so that the high idle solenoid would not do anything even if it were working. I think it might be time to replace both of those solenoid and then take it in for a tune up.
 

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I had a thought today and checked my Cold Timing advance solenoid and High Idle solenoid.
yeah my cold advance and high idle are both non functional as well, so i wouldn't worry about them. the cold advance doesn't help starting at all. its purpose is to eliminate smoke at startup (for those starting in cold garages).

if you're confident its not fuel delivery (i'm not), then look elsewhere. i kind of doubt compression. perhaps the pre chambers are full of black stuff. maybe some kind of scope to see in thru an injector hole.
 

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Discussion Starter #26
I'm not sure where to go now. I think I'm going to go ahead and get the HPCA relay fixed because i was reading about how the DB2 pump works and its my understanding that the HPCA relay opens the check valve that comes off the governor cover. This changes the pressure difference on both sides of the advance plunger and advances the timing by 6 degrees putting you closer to TDC during cranking which in turn leads to easier starting.

However I don't think I will worry about the high idle solenoid.

After I replace the HPCA I'm going to have my friend check the timing. He's got two timing gauges for the 6.2. One uses a luminosity probe and the other has a piezo sensor that goes on the injector line. Both of them time off of the dimple/notch on the harmonic balancer.

We'll see what happens.
 

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Discussion Starter #28
So I changed my glowplugs this afternoon. All of them were missing the ends, AGAIN. It's like they are melting off or something. The last time I chalked it up to running them off of 24V without the resistor pack. This time they did the same thing on 12V. I just cranked the engine and blew out the debris. I heard some of it fly out. I had one plug that I couldn't pull by hand so I just unscrewed it all the way and then cranked the engine. Shot out like a rocket.

Then I TRIED to run a compression test using the tester from harbor freight. I put the adapter in, plugged in the gauge and cranked the engine. I could see the gauge from the cab and I saw the needle hit 300 psi before the hydraulic fitting blew apart on the hose. I'm guessing that indicates good compression but I'm going to take the tester back and get a replacement and try again.

I think my starting issue is timing and a back HPCA relay.
 

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Have u replaced your glow plug controller? I was a mechanic in the army and changed many glowplug controllers, and maybe one set of plugs. I usually worked on hummers, but I think the blazers had identical 6.2 in em.
 

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Discussion Starter #32
I switched to a manual glow plug control. Just a relay with a button on the dash. I put in new glow plugs sunday. Still crazy hard to get to start by cranking. 1/3 second spritz of ether and she jumps up and idles. A friend helped me adjust the timing yesterday. We set it to 8.5 degrees. No noticeable difference in operation. I think the injector pump is just worn out. It is 26 years old.

Theres a stanadyne dealer/service center on Broadway here in St. Louis so I'm going to give them a call and see what they think and what sort of services they offer. It says they do repair and rebuild.

The only thing I was confused on was that the scribe marks were totally matched. I expected we needed to advance the pump a little. I think what we did though was set it back to spec timing. He rotated is toward the passenger side about the width of three dimes and said that it was 8.5 degrees. Everything I see says that advance is toward the driver side. Anyone know for sure?
 

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yeah, a worn out pump is the most likely culprit. you could run it on straight pump fuel to be sure. it should start worse on pump fuel if it is a worn out pump. or you could run a thicker blend, and it should start better. my db2 is also worn out. it will not warm start at all (not even close) on pump fuel. pour a little water on it, and it fires right up instantly. my 50/50 mix is a little thicker than pump fuel. it always starts perfect with the mix (hot, warm, or cold). my pump is only 19 years old.

thanks for that web link. $255 is a decent price i would say. they want $450 to rebuild my db2. not sure why. must be more parts inside the later db2s. i'm gonna have to start saving my pennies.
 

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Discussion Starter #35
Scratch that place. I did some looking. They have nothing but horror stories on the internet and the BBB gives them a big fat F.

Same on the other cheap rebuild deal on ebay.

I'm just going with the local stanadyne dealer here in St. Louis. They have multiple accredidations.
 

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Discussion Starter #36
Well I ruled out the last possibility. I did an annotated compression test tonight. I could only get the harbor freight tester to connect to the four gp ports on the driver side. The adapter had interference on the passenger side from the exhaust manifold. In any case I read 400 and change on all four cylinders and thats using to different pressure gauges because one of them stopped working halfway through and I had to take the gauge off the other one that broke on sunday to make one working tester.

So I've ruled out everything. I feel fully comfortable in my analysis that it is the %100 injector pump. Oh yeah. And the glow plugs I installed last sunday? every tip was melted off. So there's another $70 down the toilet. Based on what I read that when the IP goes it will start melting glow plugs because the timing is off and more heat is being held in the cylinder or they are getting sprayed down with fuel at the wrong time and melt away when the fuel catches instead of it catching while atomized.

In any case, mystery solved.
 

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you sure the melted plugs aren't an electrical issue? are they seeing the proper voltage?

ip is the likely culprit. did you definitively rule out air in lines and proper fuel pressure to ip?
 

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Discussion Starter #40
Checked my fuel pressure last night. 8.5 psi feeding into the injector pump. Gauge only goes to 10. That was a idle. I didn't bother revving the engine. Anyone know what a fualty CDR valve would do? stuck open or closed conditions?
 
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