Any SBC TBI gurus out there?

[jlhollowx13]

Another quick update. Stopped by with my work truck and decided to try to jump it/boost the battery. I kept turning it over for awhile, sprayed some ether and it eventually fired up with a little white smoke. Was it flooded and not getting spark? Drove it to work and parked it until later today. I also turned it off and on a few times. It started each time, but the fuel pump didn't prime each time and it seemed to have a slightly harder time starting than normal.

Still not sure and will keep messing with it but wanted to give that small update.

 

[jlhollowx13]

Put a vise grip on the return line if you can find a rubber section of it.
Force maximum pressure, by blocking the outlet to the regulator.
Then start it.
If it starts perfectly, put a new fuel pressure regulator in the throttle body.

Fuel pressure regulators fail intermittent like that if they bind or stick.

Thanks I will try this. Do I need to block the return line in this case? I do have a rubber line coming off the passenger side return line I can block.

 

[trainbufftony]

Thanks I will try this. Do I need to block the return line in this case? I do have a rubber line coming off the passenger side return line I can block.

Try that as your next diagnostic step.
Next time it won't start, clamp that line and force fuel pressure to test weather the regulator is failing intermittently. Do this by blocking the return line to the tank.
Capice?

 

[jlhollowx13]

Try that as your next diagnostic step.
Next time it won't start, clamp that line and force fuel pressure to test weather the regulator is failing intermittently. Do this by blocking the return line to the tank.
Capice?

After work today I swapped my fuel pump at the shop at work. It started and ran until it got warmed up, then it died and wouldn't start again. I clamped the return line with no change.

I had some coworkers come back from a job so I finally had someone there when having the issue. We confirmed no spark and the ignition I was getting from the ether must have been compression, or dieseling I learned today. We recreated it again. I'm still not getting any codes, I'm thinking maybe it's the coil at this point. Wasn't getting any spark from the coil or the one spark plug wire we tested.

 

[too tall]

I would check the pickup coil in the distributor. They have been known to get chewed up by the rotor shaft if the bushing in the dizzy goes bad. Very intermittent and seemingly not related issues can arise. One of them being fuel pump and injector triggers. Also have had the temp sender for the ecu cause lots of weird runnability issues.
Also as a note you should run a steel inline filter rather than a plastic one on fuel injection systems as they tend to swell at times as the pressure goes up and down eventually they crack and can become a fire hazard. Probably not causing your problems though.

 

[jlhollowx13]

I would check the pickup coil in the distributor. They have been known to get chewed up by the rotor shaft if the bushing in the dizzy goes bad. Very intermittent and seemingly not related issues can arise. One of them being fuel pump and injector triggers. Also have had the temp sender for the ecu cause lots of weird runnability issues.
Also as a note you should run a steel inline filter rather than a plastic one on fuel injection systems as they tend to swell at times as the pressure goes up and down eventually they crack and can become a fire hazard. Probably not causing your problems though.

Thanks, I am running a metal filter on those that I install. I was just reading another forum about what you mentioned with the distributor. Maybe I'll toss the other one I have on the parts truck in and see.

 

[jlhollowx13]

I'm reviving this thread. I thought I got it figured out, there is a jumper wire between the coil and distributor and it was bad. Used the one from my parts truck and it gave me spark and fired up.

Been driving it for about a month, then recently noticed it would kind of seem underpowered/not getting enough of something when getting on the gas. Then one day it wouldn't start for my wife and will not start.

I am getting spark, will fire up with ether. Fuel pump does NOT run and will NOT prime when key goes from off to ign. Wired fuel pump direct to power source and it runs so I think it's good (and only a month or 2 old). I think I'm still chasing the initial issue I was having with no fuel. I tested the injectors with a 9v battery and hear a click. Changed out the ICM with the spare i had and no change. Also tried my other fuel pump relay with no change. Fuses in fuse panel are good.

Been reading other forums, etc and most people have no spark and no fuel, not just no fuel and most of the time if just no fuel it's something like the fuel pump, also read bad ECM. Wondering if anyone has ideas of what to check next. I believe the ICM controls both spark and fuel, not sure what else is involved or if anything controls the fuel besides the relay.

 

[aztoyman]

Do you have an electrical schematic to work with?

At what point did you put power direct to the pump? If it (the pump) ran and you have spark, it sounds like a wiring problem.

IDK if the ignition switch can be failing since I don't know how the circuit is wired. But it sounds like it works if you get power to the ignition and get spark. It lets you crank over the engine.

In key on, It sounds like It didn't activate the pump relay or the relay isn't turning on the pump and something isn't telling the computer to activate the injectors.

Post up the wiring schematic if you can.

 

[aztoyman]

Also, I've had dirty contacts in fuse panels fool me into thinking there was continuity in the circuit. A good fuse still needs a clean contact so verify with your meter.

 

[jlhollowx13]

Do you have an electrical schematic to work with?

At what point did you put power direct to the pump? If it (the pump) ran and you have spark, it sounds like a wiring problem.

IDK if the ignition switch can be failing since I don't know how the circuit is wired. But it sounds like it works if you get power to the ignition and get spark. It lets you crank over the engine.

In key on, It sounds like It didn't activate the pump relay or the relay isn't turning on the pump and something isn't telling the computer to activate the injectors.

Post up the wiring schematic if you can.

No I don't have a schematic. I just put power direct to the pump today. I didn't try starting the engine with power to the pump, just wanted to see if the pump would run. Used a little 120v to 12v converter to test it.

I got some help to turn the key while I'm in the engine bay. I'm not feeling either of the relays I have clicking. I do get power on the main power wire in the relay harness. I may run into town and grab a relay. I live pretty far away from the auto parts shop so I was trying to narrow it down as much as possible before I make the trip. I'll dig into the relay side a bit more before I make the trek, maybe there's a way to test it.

 

[aztoyman]

Maybe see if it starts and runs with the pump powered up directly like you had it?

 

[aztoyman]

Sorry, I just re-read your post and you said it runs with the pump directly wired.

Check wiring from key switch to relay and relay to pump. Good luck with it. I know it's frustrating.

 

[jlhollowx13]

Sorry, I just re-read your post and you said it runs with the pump directly wired.

Check wiring from key switch to relay and relay to pump. Good luck with it. I know it's frustrating.

Sorry, I wasn't clear. The fuel pump runs when connected to power. I didn't try starting it doing that earlier but did just now and it did not start. It sputtered for a second but then just cranked. So no, it does not start when the fuel pump is hardwired and running.

I ran to town to grab a new relay and a couple other things. Unfortunately they didn't have a relay.

One other thing I'll note is I have a check engine light bulb wired in. It used to come on when the key was turned to ignition. Now it does not. I thought maybe a burned out bulb so I got one in town also and it still does not illuminate when the key is turned how it's supposed to. Not sure if that's indicative of something.

I'm headed out of town tomorrow for the week for work, so I won't be able to look at it any further until I'm back. In the meantime I will order a new relay, and possibly whatever else.

I removed the wire at the coil again and got good spark off the coil. Maybe a new distributor cap will be ordered as well if they are cheap. I have the 2 used ones that look good though.

Another thing is i tested the volts off the fuel pump relay harness. 1 seemed to be ground, 1 was always powered and the other 2 i didn't get power to, even with the key on. So maybe something else indicating something? To me it almost seems the computer isn't communicating, but I don't want to jump to conclusions and also I'd suspect spark wouldn't be present of an ECU issue.