Just installed a crate motor-starting issues-HELP??

[hmdznrcld]

Ok I just finished installing a 94 3.4L DOHC into my 91 GP GTP, After plugging everything in, checking for leaks etc. the new baby won't fire off.

 

I made sure I primed the oil pump

I rechecked the plug wires

I tried reversing the crank sensor wires (then put it back the stock way)

I rechecked to make sure the injectors (car was running before with same ones)

It has new plugs

I did add a little oil to the cylinders before the pump was primed.

 

I checked the fuel rail for pressure but did not get a large burst of fuel, I know that there is only about 2.5 gallons in the tank. Could the be the issue? Need a half full tank?

 

 

I did notice that my nephew forgot to tighten the alternator wire fully, I would think the car would run though just not charge the battery.

 

 

Any help from you gurus would be looked at kindly

 

 

 

 

 

 

[slick]

Does it crank? Starts, sputter's, and dies?

[Breakdown]

Ok I just finished installing a 94 3.4L DOHC into my 91 GP GTP, After plugging everything in, checking for leaks etc. the new baby won't fire off.

 

I made sure I primed the oil pump

I rechecked the plug wires

I tried reversing the crank sensor wires (then put it back the stock way)

I rechecked to make sure the injectors (car was running before with same ones)

It has new plugs

I did add a little oil to the cylinders before the pump was primed.

 

I checked the fuel rail for pressure but did not get a large burst of fuel, I know that there is only about 2.5 gallons in the tank. Could the be the issue? Need a half full tank?

 

 

I did notice that my nephew forgot to tighten the alternator wire fully, I would think the car would run though just not charge the battery.

 

 

Any help from you gurus would be looked at kindly

 

 

 

 

 

 

 

The alternator is the power source the car's electronics runs off of - not the battery. The battery just starts the car, and can carry things like the radio or power windows when the car's engine is off.

[hmdznrcld]

It just turns over, no firing yet. I did check the spark with the plugs out and it appears to sparking.

 

So if that wire on the alternator is not tight the car won't start? Everything lights up.

 

 

[Addicted To Boost]

It could have a bad crank position sensor. If that sensor is bad, it will have spark, but not at the correct time for it to fire.

[slick]

There should be a fuel pump relay jump test point, there by the AUX post under the hood. Connect that up and listen to see if your fuel pump is going.

[Crazy K]

spark or no spark?

 

I missed a smaller wire that it hooked to the aux post on my 92, and the car would not start. should be similar to 91...

[ManicMechanic]

It just turns over, no firing yet. I did check the spark with the plugs out and it appears to sparking.

[hmdznrcld]

mm let me clarify, the plugs seem to be getting spark but there is no combustion happening to make the car start.

[Andrew]

you swapped ECM's too right?

[jman093]

94 is the first year of sequential fuel injection. When switching to SFI did they maybe change the number of reluctor wheel teeth for the crank sensor or something that would throw off the accuracy of the crank sensor? SFI engines uses a cam sensor as well, but If you're still using the original ECM and injectors I don't think that would matter at all since it does not need cam position.

[hmdznrcld]

I actually kept the ecm 91-93 are the same. I was wondering about the crank sensor, I did try to reverse the wires to no avail.

 

Something is a little wierd though, I have to pull the uim to change the plugs, there is NO room to get to them, I sure hope I don't have to do that again for awhile.

 

I am sure it is something very small, I just need to figure out what it is

 

 

 

 

 

[White93z34]

first off be sure you are getting proper fuel pressure, if you question it at all get a gauge on the rail and see what it is putting out.

 

are you using your original rail and injectors?

[Addicted To Boost]

It could have a bad crank position sensor. If that sensor is bad, it will have spark, but not at the correct time for it to fire.

[CSI_MuNkY]

I actually kept the ecm 91-93 are the same. I was wondering about the crank sensor, I did try to reverse the wires to no avail.

 

In your original post you said the new engine was a 94... if thats the case you need the 94 ECM... I might be wrong, but didn't the dreaded OBD1.5 start some time in 94? or was it only 95?

 

Jamie

[slick]

94 is the first year of sequential fuel injection. When switching to SFI did they maybe change the number of reluctor wheel teeth for the crank sensor or something that would throw off the accuracy of the crank sensor? SFI engines uses a cam sensor as well, but If you're still using the original ECM and injectors I don't think that would matter at all since it does not need cam position.

 

No, it will work MPFI. In fact, early SFI cars run SFI for a short time, then switch back to MPFI.

[Pontiac6KSTEAWD]

The alternator is the power source the car's electronics runs off of - not the battery. The battery just starts the car, and can carry things like the radio or power windows when the car's engine is off.

 

Partially incorrect. A car can run, and drive, just fine off a battery with sufficient energy to power the coil packs. Its when the battery has lost the charge that the coils need that the engine will die. This occurs at diferent levels depending on the power consumption of the coils. I think the 3.1's run out of juice when the battery hits about 8-9 volts.

 

Back on topic..

 

I agree with seeing if you are getting fuel pressure at the fuel rail. If you are, would probly suggest you fill a gas can up with 2 gals of gas, and put it in the tank. At least then you can eliminate the idea that there isnt enuf fuel for the fuel pick up to get at.

 

I would also suggest spraying in some starting fluid into the intake, and turning it over to see if she would start. But I would be so leary of doing that with a crate new engine. Maybe one of the other members can clear up whether that would be safe of not.

 

The reason I suggest this is, if it starts, and runs ok off the starting fluid, at least then you know its fuel related and not spark/electronic related.

[Crazy K]

is the upper intake manifold different???? does the throttle body seperate from the upper intake? that would indicate a 96-97 motor.... but it should still work. *Psychomatt has a 96 motor in his 94*

 

and i plan on using a 94-95 motor in my 93..............

[hmdznrcld]

I am using the 91-93 UIM & LIM I basically pulled everything off the 91 motor and bolted it up. I am going to buy 5 gallons of gas today and add to the tank, that would give me about 7 total, should be more than enough.

 

Will post later Thanks for all the help.

 

This is going to be one sweet car, the interior is a 10. in my book for the age. Back buckets look to have never been sat on.

 

 

[GP1138]

Weren't there changes in cam sensor placement between the earlier and the '94+ motors? I might be all wet on that.

[Crazy K]

Weren't there changes in cam sensor placement between the earlier and the '94+ motors? I might be all wet on that.

yes.

 

but newer motor can go into older car, not the other way around.

[GP1138]

Weren't there changes in cam sensor placement between the earlier and the '94+ motors? I might be all wet on that.

yes.

 

but newer motor can go into older car, not the other way around.

 

Maybe there's a difference in cam sensors or it's reading the wrong thing or something, I'm not sure. I'd need to read more about it. I DID have a point to what I was asking.

[spiderw31]

Maybe there's a difference in cam sensors or it's reading the wrong thing or something, I'm not sure. I'd need to read more about it. I DID have a point to what I was asking.

 

The way I read it, he has the old electronics hooked up the the motor. In that case, it doesn't even use the the cam sensor.

[hmdznrcld]

OK here is what I have done so far

 

Still nothing!

 

Surely a long block crate motor would be in time from the factory right??

 

 

1. Checked and rechecked plug wires (buddy of mine verified too)

2. Installed new fuel pump, sock and harness, getting plenty of pressure to fuel rail

3. Verified spark to plugs

4. Verified injectors getting fuel

5. All connectors plugged in.

6. Verified harness in.

7. Primed oil pump now getting 45-60 lbs during cranking

 

 

Any other things I should check? I am sure it has to be something small that I am overlooking

 

TIA

[BIGBULS]

Something is a little wierd though, I have to pull the uim to change the plugs, there is NO room to get to them, I sure hope I don't have to do that again for awhile.

 

As a side note:

 

You do NOT have to remove the UIM to do the plugs/wires.

 

Pull out the dogbone (engine torque mount that goes to the radiator shroud), and crank the engine foward. The lower mounts don't even have to be losened, and it makes the job a BREEZE. One of my techs has a special tool that you put in place of the dogbone and looks like a reverse scissor-jack.........just hook up an impact, and it takes mere seconds to crank the engine foward.

 

 

 

 

 

 

But as for your crank, no start issue..........sounds like a fuel issue of some kind.