I've done a TPI 350 swap in my 88 Supra, I'm trying to get this thing running, but so far, all I've been able to get is a few pops then just cranking over.

It will make a few half assed attempts at firing a few cylinders but then it just goes to cranking.

So far what I know is that the injectors have power, and I know it isn't the most accurate, but my test light shows at least one on each bank is pulsing. I know I'm getting good spark, I know fuel is getting into the cylinder at some point, the plugs were wet, there's pressure at the rail after the pump primes, as well as after cranking, but I don't know how much as I haven't been able to put a gauge on it yet.


So far all I've been able to work out is all related to the injectors.

The computer completes the ground circuit to fire the injectors, right? I've got almost completely solid mounts, and they give enough of a ground without a strap to ground the starter, so I don't think it's anything that simple.

My other thought was leaking injectors, but without a gauge, I can't confirm that.

My other thought was the fuel pump. I bought a used harness that somebody had already cut and shut. So far everything I've found has been correct, no hack job with the wiring, but one of the things they cut out was the oil pressure switch wiring to the computer. Does the computer absolutely have to see that circuit to power the fuel pump after cranking? I have oil pressure during cranking, I have a gauge hooked up, just not to the computer.

Any other ideas or recommendations on where to start?

I've got my ALDL coming from Moates tomorrow, I was going to plug that up and try to see if I could get some insight that way, as well as rent a noid light and pressure gauge and test the fuel rail and injector pressure.

 

You are correct that the ECM grounds the injectors to fire them, the ECM gets its ground through several ground wires that ground to the back of the head. If you have injector pulse while it's cranking your grounds and source voltage is good.

You will definitely need to know what the fuel pressure is while cranking, low fuel pressure will cause the symptoms you are having for sure.

Also if the engine has set for a long period of time the injectors could be clogged causing start issues as well.

Have you tried spraying starting fluid in the TB and see if it starts that way?

 

Okay, so I can rule out injector electronics.

I will check the fuel pressure as soon as I can, other than leaking injectors, what can cause a fuel pressure drop like that?

yes, we sprayed maf cleaner in it at some point and it wanted to run on that.

I know the intake was sitting by itself for some time, although it was assembled when I got it.

So you would lean toward the injectors being mechanically faulty?

 

If fuel pressure is good then yes injectors would be the next suspect.

You can check the coils with an ohm meter, each injector should measure 12-15 ohms.

If the engine has been setting for a while the injectors may just be gummed up.

 

I forgot to mention that the injectors had like 12 ohms or less when I checked them. I thought that was unusual, but I figure lower resistance can't be too bad of a thing.

I guess I should just go ahead and take the opportunity to upgrade my setup and get some better injectors.

 

How long has the motor been sitting before you got it swapped over and tried to start it?? Me and my dad have swapped 5 tpis now into other cars. Most of the time it's a long time from the time we start the swap until we actually try and crank the tpi. Each time we have had to get new injectors before the car would run right. Several times the motor set a couple years and all we had to do was swap out the injectors and the motor ran fine. If the car will hit a couple times with some starter fluid sprayed into the intake I would bet the injectors are bad and need replacing. Rebuilt injectors from Southbay or Ebay are not that expensive now days.

 

Update:

Swapped out the injectors for some 24lb/hr ones out of a Lincoln mark 8.

I ran cleaner through every one, tested them all, they all worked.

Noid light shows that all injectors are getting signal.

Still does the same thing...

I'm wondering now, I have a solid flat tappet cam, will the knock sensor pick up the vibration and retard the timing enough to keep it from starting?

I'm out of ideas here and starting to pull my hair out lol

 

Have you done anything with valve adjustment? Rocker arms being too tight will cause no start as well

 

I halfassed it and just tightened them til the pushrod wouldn't spin, but I haven't gone and done a full proper adjustment. It's got good compression so I figured I wasn't hanging any valves open.