Throttle body issues

[Chevy3+3]

Ok answer me this. Are your injectors pulsing fuel while you are cranking the engine?

[Chrispbrown36]

They are not pulsing while it is cranking. I noticed today that they are just dripping. I thought it was strange but when it would fire up with gas down the bores I kind of ignored that and moved on to an ignition issue. It isn't a constant drip either...just kind of one drop out of each injector every ten seconds or so.

[Pano]

Sorry I can't help but I am interested in this thread. Before I took a TBI 454 out of a 1991 RV to put in my truck I heard it run for about 5 minutes and it seemed to run well. It stalled and had the same drip out of the injectors. I spent a little time trying to figure it out but ended up pulling the engine before it was fixed. I plan to put it n the truck next year.

[Chevy3+3]

Originally Posted by Chrispbrown36

They are not pulsing while it is cranking. I noticed today that they are just dripping. I thought it was strange but when it would fire up with gas down the bores I kind of ignored that and moved on to an ignition issue. It isn't a constant drip either...just kind of one drop out of each injector every ten seconds or so.

I really think you need to find another distributer and swap into it. If you replaced your ICM and you still don't have fire it would almost have to be that your pickup coil is bad. The oil pressure sending unit also stops the fuel system if it were to go bad. But I cannot confirm if it kills your fire also.

[Chrispbrown36]

I tested the pickup coil a few weeks back and it tested good. Couldn't I just replace the pickup coil?

[GM_For_Life]

Originally Posted by D13

SO, if you prime it and it fires than the spark is there which says the distributor is close and the module is at least functional. So no fuel is either pump failure, relay failure, ECM failure, or wiring. Assuming it ran before, most likely is disconnected wiring harness, check at fuel pump relay first. When you turn the key on without cranking the ECM commands the fuel pump to run for a couple seconds. If it does that then there should be pressure at the fuel rail tap. But my bet is a disconnect between distributor, ECM, fuel pump relay, or injector harness.
You did make sure the ground wires at the back of the engine are hooked up, right? Grounds are critical on injected motors.

Had an 88 v10 that did something very similar to OP's problem, replaced the ECM after much heartache and it fired right up. Above are the usual suspects

[Chrispbrown36]

I checked the spark on all wires from the distributor today and all was good there. I also had a spare ECM I plugged up and still no start. I swapped the old ignition control module back in because at least when I had it in there it would fire up with gas in the bores.....still no start but it did backfire a little while cranking....possibly have the distributor 180 off? I think tomorrow I am going to pick up a new oil pressure switch and swap it out. The one in there looks like it might be original so I figure for 10 bucks it can't hurt.

[Chevy3+3]

Ok first of all you should be injecting fuel when your cranking. That can be controlled by several things as many have mentioned above. One other thing which can be overlooked is do you have dual tanks? Sometimes the switch in the dash can go bad or be stuck between the left & right tank position.

Another thing is if you have spark but it won't start even if you dump fuel down the bores them your timing has almost gotta be off. You need to wait for #1 cylinder to come up on compression stroke. When it starts building pressure then take a straw or screwdriver and insert in the spark plug hole. Slowly crank the motor over by hand until the straw or screwdriver quits pushing out. Once it stops pushing out you need to see if your rotor on you distributer is pointing close to the #1 plug wire. If it isn't then your timing is off.

If for some reason your distributer is 90° off instead of 180 then you will most likely need to re-index the slot in the oil pump shaft so that it lines up with the orientation of where the distributer drive gear needs to be to make the rotor point at #1 plug wires. Once you get it started you will need to set the initial timing with the ECM wire unplugged usually located around or under the brake master cylinder. It will be a single brown wire most likely with a black quick connect plug.

[Chrispbrown36]

It does have dual tanks, but the other tank is off and the switch hasn't been moved since I bought the truck.
I meant 90 off not 180. I set the timing just as you described, but as soon as it blew my thumb off (after I felt the suction) I stopped bumping it over....did I maybe not let it finish the stroke?

[Chevy3+3]

Originally Posted by Chrispbrown36

It does have dual tanks, but the other tank is off and the switch hasn't been moved since I bought the truck.
I meant 90 off not 180. I set the timing just as you described, but as soon as it blew my thumb off (after I felt the suction) I stopped bumping it over....did I maybe not let it finish the stroke?

I bet it didn't finish the stroke. You really need to have that piston at the top of the cylinder when you stabbed the distributer back in. If you didn't then I can almost guarantee your timing is off

[Chrispbrown36]

Ok....it's a step forward, but I am back to where I was. My distributor was off, but I am back to the point where I can dump fuel down the bores and get her to fire up. As soon as the fuel is burnt it dies. Not getting a spray, just a little drip out of the injectors. It looks like I am going to pick up a new distributor tomorrow....man I hope that's it.

[Chrispbrown36]

Ok, now the pickup coil is new and still the same problem. I have noticed that the injectors are dripping a little more quickly than I had noticed them doing before. I tested the voltage at the injector harness while cranking and it never got much over 1 volt.

[pontgta]

Really looks like fue delivery. Either injectors are bad or fuel pressure. How did you check fuel pressure? Hopefully inline.

[Chrispbrown36]

Inline before the fuel filter. I am confident it isn't the fuel pressure or injectors. The fuel pump was just changed and the injectors test fine when pulsed on a direct 12v source.

[Chrispbrown36]

And another development....Went out to mess around with it some more and noticed that the pigtail running from the coil to the ignition module looked a little odd. I bent it a little and it broke off. So, I guess tomorrow I will be stopping by to pick up a new pigtail....maybe this is what has been causing the trouble all along.

[Chrispbrown36]

I am beating my head against the wall over this. Here is where it sits....I have 12 volts on one side of the injector harness on each injector with the key turned on, I have a pulse when it is cranked (noid light and can hear/feel it while cranking), and I have continuity to the battery off of the grounds on the passenger side head and front of the intake. When it is cranked the fuel is still dripping out and when you stop cranking it will sort of spray, not the mist that it typically sprays when running correctly, more of a spray of big drops. I also hear what sounds like a relay clicking when it stops cranking for a second or two, but I can't pin down exactly where it is coming from.

[Pano]

In case you have not seen this.

http://www.73-87chevytrucks.com/tech...TBISystems.pdf

[cadillac_al]

Did the new fuel pump give you any more pressure? It looks like the above link from Pano will get it diagnosed.

[Pano]

Crisp, did you get it working?

[Chrispbrown36]

No I did not. I have decided she is going to sit until I can get it into a shop and have someone else look at it. I have spent enough time and money running down the issue I might as well pay someone else that should have better tools and facilities.

[Pano]

Copy, please post what the shop finds out. I have the same symptoms on a motor I plan to put in my truck and would like to know.

[Chrispbrown36]

Will do.

[Chrispbrown36]

Ok, so I decided to throw a new distributor in as a hail mary. While I was dropping it in I noticed that when I dropped it in I would hear the fuel pump kick on. I thought that was a bit strange, so I started looking around thinking I had pinched a wire some place. While I was messing around with it I noticed a spark coming out of the coil wire and that each time I would drop the distributor in the fuel pump would prime...like I had turned the key to the on position (it was in the on position the entire time). This doesn't seem normal to me. It makes me think there is a short some where. Any ideas?

[Blessed66]

Originally Posted by Chrispbrown36

Ok, so I decided to throw a new distributor in as a hail mary. While I was dropping it in I noticed that when I dropped it in I would hear the fuel pump kick on. I thought that was a bit strange, so I started looking around thinking I had pinched a wire some place. While I was messing around with it I noticed a spark coming out of the coil wire and that each time I would drop the distributor in the fuel pump would prime...like I had turned the key to the on position (it was in the on position the entire time). This doesn't seem normal to me. It makes me think there is a short some where. Any ideas?

Did the pump kick on when you plugged in the harness or when you stabbed the distributor?

[Chrispbrown36]

Stabbed the distributor.