I have a 88 Suburban,5.7L,automatic,4x4 3/4 ton. I blew a valve seat in my old motor and replaced it with a good running used 350. I bought it from a place i've been doing business with for a long time,and they ran tested it before they shipped it to me. They left the distributor in,and all i did was switch a few sensors,and water pump,exhaust manifolds over. I dropped it in,hooked everything up,turned the ignition and it turned over but will not start. It sounds almost like it wants to start,but then it backfires through the TBI. THe first thing I thought was timing,but I DID NOT touch the distributor and the vehicle it came out of was running fine the was it was sitting. I was told from one person that it could be poor fuel pressure,and to shoot some carb cleaner down one of the injector holes on the TBI while somebody is turning it over. Any other thoughts what it could be?

Thanks
Andy

First, I would double check the plug wires to make sure that they are all in the right order, and that #1 is in the right place. If it was shipped with the cap and wires on it, check for a cracked cap.

That does sound like a textbook misrouted plug wire or the dizzy wasn't dropped in place right... Keep us filled in.

When was the last time the fuel filter was changed out?
Fresh fuel?
Do you smell fuel when you are trying to start?
Was it your old throttle body that ran good or a new unknown one?

You can turn the key to on, but not start, and do a visual on the injectors. Open the TB up and see if any fuel sprays out of the injectors.

The good news is, this sounds like a quick fix... Sometimes the blatant problems are easier to solve then the phantom problems people sometimes get.

Did the engine come with a TBI distributator? Was it even a TBI engine? You might have to swap over your TBI dist if they sent you a non-computer controled one. If it is the right one, I'd agree with the earlier statements of miswired plug wires or the Dizzy one tooth off.

redz,
I am re-using my old throttle body that ran fine. I'm unsure of when the fuel filter was changed last,since these problems happened 3 weeks after i bought the vehicle. The fuel is a month old. Fuel is being supplied. I know this because when first trying to start it, I flooded it and put new plugs in. They were "dripping" wet with gasoline.

zoomad,
The engine came with a TBI distributor. Looks identical to my old one. The motor came with a tbi on it but the electrical connections were different as it was off of a 1994 vehicle.

I'll double check TDC on #1 cylinder and make sure of correct routed wires. I have double/triple checked them already but havent checked TDC yet to make sure that #1 wire is on #1 cylinder.

I'll keep everybody posted. I should be able to work on it tonight after work.

Thank you

Have you tried using starting fluid? Does it sound like it would run on the starting fluid? I would think if it runs on the starting fluid that there is a problem with the fuel delivery. Forgive my ingorance if starting fluid won't work with TBI, lately I've been working on chevy diesels and old Ford carbureted engines.

Update:
I have it started. I bought a new set of plug wires and for the heck of it I thought I'd turn it over. It fired right up!!!! NOW..... Does anybody have a vacuum hose diagram or something they could tell me which hoses go where. There were the old brittle plastic lines that went back and forth on top,but they all broke and I lost track of where they went. The truck starts but I can tell I have some vacuum hoses mis routed.

The old intake had vacuum post with 2 nipples on it that was between the dist. and the TBI. The new intake had a blank plug where that was. The cruise on my Suburban didn't work so I wasn't going to hook it back up anyway. What I need to know is where to put the vacuum lines from the TBI and the Electric modules to the left of it. Can I leave that vacuum post off or will I need to transfer that to the new intake?

Thanks,
Andy

wow your local to me. I have a 87 blazer with tpi if you need to look it over if you cant find a diagram.