Calling all GMC 6.5L Turbo owners! I need help!
May 29, 2007 - 7:06am
96 GMC 6.5L Turbo Great on Petro, rough on veggie?
New IP replaced this winter. Remote mounted PMD. Runs great on diesel, and will operate at low RPM (idlilng in the garage or even city driving) for quite some time before acting up. No power or acceleration on veggie, acts starved for fuel. When I switch back to diesel, it immediately starts running better. My mechanic says a "finicky" Stanadyne IP optical sensor is the problem and advised me to not run on veggie as a result.
I need advice from all of you 6.5L GM greasers out there!
May 29, 2007 - 10:55am
#2
Soinds like your VO LP isn't pushing enough VO to the IP. What do you have?
Andy
if the VP ends up MIA, you will all be on KP
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6.5 'Burb
May 29, 2007 - 11:16am
#3
Lift pump is the stock pump that came with the greasecar truck kit. I agree, it feels like fuel starvation because of the quick change when back to veggie. I'll check on all. Thanks.
May 29, 2007 - 11:35am
#4
I have a Carter somethingorother. In a little while I go out to check the exact PN.
Andy
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6.5 'Burb
May 29, 2007 - 11:56am
#5
Quote:
Originally posted by: Raven17
96 GMC 6.5L Turbo Great on Petro, rough on veggie?
New IP replaced this winter. Remote mounted PMD. Runs great on diesel, and will operate at low RPM (idlilng in the garage or even city driving) for quite some time before acting up. No power or acceleration on veggie, acts starved for fuel. When I switch back to diesel, it immediately starts running better. My mechanic says a "finicky" Stanadyne IP optical sensor is the problem and advised me to not run on veggie as a result.
I need advice from all of you 6.5L GM greasers out there!
Don't be offended, but it sounds a lot like air bleeding into the veggie side or a clogged VO filter. higher rpms = higher fule demand = higher vacuum in lines = more air bleeding in.
Later,
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sdeck
2003 Jetta TDI, GreaseCar kit, veg-therm std, TDIHeater, >20,000 veggie miles and counting!
"If you make it idiot proof, nature will make a better idiot"
May 29, 2007 - 12:08pm
#6
No offense taken. At this point, I'll try anything. So if it is air, I need to check all clamps around barbs and purge, right? Listen for bubbles in the veggie tank? Filter is new. Haven't run 100 miles on veggie with this filter.
May 29, 2007 - 12:13pm
#7
Just to clarify, I have a fuel pump for VO another for diesel and an additional one for both (just before IP). This way I have 2 fuel pumps running no matter what fuel I'm using. This has solve the fuel starvation problems.
Sdeck is right about those checks but that would be covered in the "Troubleshoot" link, if you went to that.
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An unbreakable toy is useful for breaking other toys.
May 29, 2007 - 2:08pm
#8
Quote:
Originally posted by: Raven17
No offense taken. At this point, I'll try anything. So if it is air, I need to check all clamps around barbs and purge, right? Listen for bubbles in the veggie tank? Filter is new. Haven't run 100 miles on veggie with this filter.
tighten all clamps (they work loose after heating up the first few times you run after installing).
You did fill the VO filter before installing, correct?
I guess purging and loking for bubbles in VO tank could confirm air, if there is enough to see it. Interesting diagnostic. Remember though, the issue is only apparent under load, so there may not be much air.
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sdeck
2003 Jetta TDI, GreaseCar kit, veg-therm std, TDIHeater, >20,000 veggie miles and counting!
"If you make it idiot proof, nature will make a better idiot"
May 29, 2007 - 10:27pm
#9
Quote:
Originally posted by: real_murph
I have a Carter somethingorother. In a little while I go out to check the exact PN.
Andy
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6.5 'Burb
P61092S
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6.5 'Burb
June 3, 2007 - 3:16pm
#10
I also found that one Carter fuel pump would not fuel my 99' Burb.I now have the Carter at the tank (veg.)and a Mallory at the firewall. I haven't done this yet either but you may want to install a fuel pressure guage and some sort of "sight glass" on the return to help you see a air leak.
Mike
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Raven17,
I converted my 1994 Suburban.
Check out the Troubleshoot thread.
If, in fact, your mechanic is right and you have a "finicky" optical sensor, you can remind him that this is inside the IP that he just replaced. Odds are he'll shrug his shoulders and say "well, it runs fine on diesel". But it's worth a shot.
Here is a link to replacing the optical sensor. Not too tough. Not sure how much they cost though. Your suppose to be able to check the optic sensor by unplugging it and the system goes into limp mode.
If it runs better then it is your optic sensor.
If not, you won't know if its running bad because the optic Sensor is good or that "limp mode" is bad.
I had some problems with fuel starvation. Run through that troubleshoot check list. I added an extra fuel pump just before the IP. Got one that is a regular diesel lift pump repalcement for the truck, a couple barbed fittings amd good to go. $56 at Checker Auto. That way if the regular lift pump goes bad I have a spare to get me home or wherever.
The extra lift pump has solved the fuel starvation problems and the truck is on the way back from Fargo as I write.
Did your mechanic set the timing. If so, what did he set it at. If he can't tell you he didn't do it and is relying on the onboard computer to set it. I have found this to be unreliable. Even after the ko-ko (key on-key off) trick that resets the timing, it still didn't run right until the IP was moved. Someone else here knew the best timing setting for both diesel and VO, I forget who though. Maybe they'll chime in.
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An unbreakable toy is useful for breaking other toys.