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Code 56. INjection pump resistor

I gotta rig the can up to roll so I can test drive to confirm that fuel supply is the main issue so I can figure that out then I guess move on to timing etc.
 
That timing is low, even on OEM the desired timing is around 8 degrees. But base timing is set to 3.5 degrees which gives a TDCO of about -0.5 to -0.75

Can you pop off the glove compartment and get a look at the chip in the PCM. It should be BPDP for an L56, make sure its that and that its stock. That code was used in 94s built in 93 with 5067 IPs, which is the same scan code your 94 Blazer friend had, which certainly wouldnt be for a 5068 IP. Which IP do you have?? You can look in the door jamb and see what month/year it was built on the top corner of the sticker. You can see from your snapshots of his he had better timing at least and he has the wrong dang IP.

I dont know if pre-94 has significance, but service bulletins made the distinction, and they made updates for them. It should be fully compatable with 5521 IPs, but I did have one of this vintage that performed exactly like your is with low idle timing and high fuel rate. I put my L65 chip back in and everything was great. When I ran it with that older L56 chip it had poor throttle response, high RPM shifts which were rough, and just sucked balls. Couple that with crummy fuel supply you could get stalling.

I can send you a better chip to test with if you want.
 
Ive never seen my temp gauge go over 195 degrees, but Ive seen GMTDScan go to 208 on a long hill climb. So I changed the sensor in the head and nothing changed. I might replace the ECT sensor on the thermostat housing, but its not causing me any grief, its hard for me to get the darn thing warn to even do timing. I have a 180 T-stat and stock cooling.
 
I'll see which IP/chip and try to do a fresh snapshot. The knocking could even be residual air in the system. My Tahoe took a good 20 mins of driving to get all the air out and it sounded horrible till it did.
 
Well, Da patient was hooked to an IV tonight and ran pretty good overall. The loud knocking disappeared and was most likely air. After I got it home I filled the fuel tank to the tippy top and hooked the factory LP back up Seems to run ok. Has a slight shudder from 1000-1400RPMs. But the eninge has 180K of what appears to be hard miles. OS could be dirty, INjectors dirty or weak and so on . But IP seems to be alive. I think I may spare it from the torch. Can imagine what the neighbors must of thought with me driving it around the Hodd with the 5 gal sitting on the hood....BTW factory fuel pressure kinda sucks on thse huh ? I was getting about 3 psi with fac LP hooked back up. I was feeding it 15 psi with the Raptor power IV. Truck was likin that Raptor..Like crack...
 

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So is a poll in order ??? Keep the 94,, sell the Lemon ???
:D
You know someone at one time had some pride in this truck. it was all pinstriped and had custom 6.5 diesel lettered on the tailgate. I wonder if it has a westers chip or something. Feels like it goes pretty healthy. But that could be mental after getting out of the CUCV.
 
Not yet but now might be the time since I think I'm going to spare it's life. Supposed to rain tommorow so probably not tommorow. The more I look at the truck the more I think it would be a shame to torch it although I really do lke the front seat, I can buy a seat from a junkyard out of a gasser. I'll feel less guilty.
 
Any ideas what could cause a shudder from about 1200 to 1600 RPM ? Clears right up above 1600 and idles fine. didn't see any noticable smoke.
 
no, this is in neutral. Not running the AD, back on it's own LP. I will try to take another screen shot but I don't think timing would cause a shudder/mild miss. I was thinking of putting a fresh fuel filter in and filling it with red 911 to clean it out a bit. It's not horrible. I just notice it. I may fix a few more things and put that baby up for sale. since the turbo setup off it isn't going to work anyway on the cucv and I am contemplting keeping the 24v starting system no sense in chopping it. It's a nice little truck. Other than needing the brakes bled it drives nice.
 
Fill the FFM halfway with ATF, run a couple quarts of SAE30 in the fuel tank and relearn the TDCO when its warm. If the timing is advanced past -1.5 back it off, if the timing is only advanced less than -0.25 advance it a little.
 
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