It was converted to carb....

[Tnrknght]

Alright so I have that anomaly 88 gmc square body that I can't actually find parts to match, but that's beside the point. To my understanding, the previous owner converted it from tbi to carb. Not sure if it was done properly considering the wiring with open pigtails everywhere and the ebay fuel pressure regulator that reading 15psi of fuel pressure as it spits out of a fitting in the back. No wonder the carb is giving me problems...

I do have a Qjet on there, just pulled it to have it looked at to see how bad it is. I'm just not sure what the fuel pressure should actually be at, or if anyone has a recommendation for a replacement fuel pressure regulator. At this point, any help and advice would be greatly appreciated.

 

[1987 GMC Jimmy]

It sounds like to PO or their mechanic should be run over with a TBI vehicle to teach them a lesson. I do have a few little nuggets to potentially make it better. I'd say a good median fuel pressure for a carb setup is 5-6 PSI. It can be a little higher or lower, but what you have now is approximately triple what is ideal. Was an older motor swapped in with a hole for a mechanical fuel pump, or is this the original motor? Another thing to consider is converting it back, and it sounds to me like it wouldn't be that hard. It sounds like most or all of the wiring harness is there. I'd even bet a few of the sensors are still there and maybe even the ECM. I personally like TBI, and I would be tripping over myself to switch it back just because I hate half ass motor and/or fuel system swaps. My brother bought a '93 K1500 that came with a 4.3 and a more advanced PCM setup, and they swapped an early TBI 305 in it and did every no-no in the book. I helped him fix most of the obvious stuff, but it's still crappy. I wouldn't throw the Quadrajet in the trash or give it away, though. I'd save that guy for later.

 

[Tnrknght]

To my knowledge it's the original motor, I really have no idea if the ecm is there or not. Quite a bit of this thing was half-assed and being an entirely different platform than my comfort zone, even knowing the 5-6 psi helps to know. I knew 15 was high, but I've also never worked with carbs.

So now I'll have to check through and see if there's any hacked wiring within the rats nests. I can only imagine what else they've messed up. I know something is tangled behind the gauge cluster to where I can't pull it out to replace the pcb on the cluster.

 

[Cuba]

So now I'll have to check through and see if there's any hacked wiring within the rats nests. I can only imagine what else they've messed up. I know something is tangled behind the gauge cluster to where I can't pull it out to replace the pcb on the cluster.

It could be just the speedometer cable? hanging you up. They seem to be quite snug behind the cluster sometimes. Feeling around back there may help.

+1 on 87 Jimmy's comment

 

[1987 GMC Jimmy]

Yep, second the speedo cable. The only other things hooked to the cluster are the VSS buffer and the electrical connector.