1988 Chevy Suburban won't start after engine swap, fuel issue?

[jonzcustomshop]

I took the oil burning engine out of my 1988 suburban and replaced it with an engine out of an 89 suburban that happened to be a newer Good Wrench replacement motor (350).

I have tried to start the engine and it seems to not be getting any fuel. If I pour some fuel into the throttle body it will run for about 15 seconds, but then it dies. I assume that I'm not getting fuel from the tank. Is there anything that I might have missed?

Both of the engines ran before the swap.

[joe231]

Does the fuel pump run?
Posted via Mobile Device

[jonzcustomshop]

I am trying to figure that out, is there an easy way to tell?

[joe231]

Get someone to turn the key on while you listen at the gas tank filler with tge cap off.
There should also be a red "test" wire at the fuel pump relay on the firewall. You can supply that wire with 12 volts to see if the pump runs.
Have you checked all your fuses? Did you double check all the underhood wiring?
Posted via Mobile Device

[ghettoluxury]

Make sure you have a power wire going from your battery to the alternator. I had this exact problem with my tbi motor, it would run if you fed it gas but would not stay running the battery cable was the problem.

[jonzcustomshop]

thanks, I will check out in the morning, and get a report back!

[85sierraclassic]

check and make sure you oil pressure sensor is the same prong count if you didnt use the original they will still plug in but one has one less prong than thee other and wont turn on the fuel pump.

[Jonboy]

If it is a bad oil pressure switch, you should still hear the pump prime when you turn the key on. The switch sends power to the fuel pump relay when it sees 3-5 psi of oil pressure (so it will shut off in event of oil pressure loss).

[legendman]

Check your grounds too, missed the one that goes from the rear of the r/s cylinder head to the firewall when I did my motor swap on my 89 K2500.
Not sure if it was the cause because I cleaned up all the ground wires when I was troubleshooting then same issue.

[jonzcustomshop]

well, got it running... everything checked out, so I tried replacing the throttle body with the one off the oil burning 88.... put it on and it just fired right up! why? I have no idea... but it works....
now that you mention that rear ground wire... i think that got missed... will have to check that and install tomorrow....

on another note; with the swap, the air pump never made it back on the vehicle... (the 89 had smog free exhaust manifolds) MT. is an inspection free state, would I benefit from removing the cat. and putting a straight pipe in its place?

[Mr Pops]

My 90 V3500 Crewcab only has one O2 sensor and it's before the cat, so it doesn't know the difference if you take it out. I did. There was no noticeable difference.

[jonzcustomshop]

ok, mainly wondering how clogged up this cat might be from the previous oil burner
when I pulled the manifolds off, it looked like #2 cylinder was not firing, and just pumping oil into the exhaust!!