Another TBI Problem (1 Viewer)

[Capt. Jim]

We swapped out the Holley 950 Commander system referenced in my earlier post for the Downey/4.3L GM system. This is in my friend Mike's truck with a 2F.

Modified a late model distributer taking out the vacuum/mechanical advance. After the install, she would not start. After fiddling with it and rechecking several times, she started right up and ran smoothly, but then died and would not restart.

Finally got her to restatrt again after more checking and again, she promptly shut down and would not restart.

Again, late last night, we got her to start up and she ran sweet for about 5 minutes. Good throttle response, smooth idle, etc. Thought we had it..........and then she died again.

Now, after triple checking everything, she won't restatrt. No spark and no fuel spray. I am indeed gettin signal fron the dizzy. Have the gap set at .008, rechecked many times and tried .006 and .010 to no avail.

Good battery voltage with no significant voltage drop from battery to ignition circuit.

Fuel pump primes up, all connections appear to be tight, using a new Painless Harness, all new sensors, fairly new distributer, (all Toyota cap and rotor),new sensors. The only thing used is the throttle body and computer.

We did no repair nor did we find any problems prior to getting it to fire-up.

Hate to be a parts-changer trouble shooter, but I don't know what to try next. My suspect items are the computer itself, which as I said is from a junkyard, or the ignition module.

Any input/suggestions are welcome. I'm getting tired and GSMTR is next week.

Thanks, Jim

 

[Isotel]

did you pull any codes?

sounds like a lose wire in the system.. maybe a ground wire

 

[Capt. Jim]

Don't have a code tester. Loose wire was my thought, too. Everything is tight that twe could see. Even did a lot of contiuity checks and checked all connectors.

 

[Isotel]

Autozone, and others have scanners for $25 or so.. they are pretty nice to have if your running TBI..

it may not solve this issue, but it may come in handy in the future.

 

[Capt. Jim]

Thanks. May go by and get one tonight.

 

[Capt. Jim]

Did the jumper test on the OBD1 socket and no codes were present.

 

[dustin]

I hate to ask obvious questons.. but- could it be a ground? Prob not if the computer itself if it gives you codes, but maybe a ground for soemthing else than the computer?

I have a TBI so am following this too.

good luck!
Dustin

 

[Capt. Jim]

We did check the grounds. Going to see another friend this morning with same system and will borrow his coil and ignition module and see what happens when they are swapped.

 

[Gumby]

Coil and ignition module are two things that will get hot and puke intermittantly. Pick up coil too.
but you said you were getting a signal to the ECM. The module will cause no signal. The coil will cause no spark, but you would still get an injector pulse.

 

[Capt. Jim]

I'm getting neither, no spark, no injector pulse.

 

[too tall]

sounds like the ignition module or the ground to the ignition module. Do you know anyone who can test it for you?

 

[Capt. Jim]

It's running again......

Thanks for all the input, guys. Seems we always overlook the obvious.



Bad ground on coil solved everything.

Thanks again.

Jim

 

[lovetoski]

So how do you like the Downey kit? Performance, install, etc?

 

[Capt. Jim]

So how do you like the Downey kit? Performance, install, etc?

Helped a friend install one on his 2F last year and he is happy with it. This recent install is on a different friends truck, 2F engine also. Both installs were fairly easy. The second was using the Painless wiring harness instead of a salvaged harness from the junkyard. I believe the Painless harness was easier because everything is labeled.

This truck still hasen't been driven yet using the Downey system. (Still doing other work on it.)

It does start right up, idle real smooth, and has great throttle response. I suspect she will drive nicely.

Both my friends seem to be pleased with them. Both trucks will be tested at GSMTR next week.

 

[FLYINGLOW]

So how do you like the Downey kit? Performance, install, etc?

Me and Too Tall have been running this setup for 5 or 6 years now and it has been pretty good. Too Tall has in on a couple trucks (2 I think). I could never get the late model dizzy to work with it and Too Tall has never tried, we both run HEI units. It makes for cleaner more straight forward swap, but you loose the sealed toyota unit. This may have changed now but the Downey kit said NOT to install the spark controler or knock sensor, which we recently found makes a big difference in performance and low end torque. If not installed it will just run in closed loop without advancing timing. I have only driven my truck once since I installed this equip, I just went wheeling for a day a couple months ago. I was very impressed with the torque, fuel economy seams to have gone up too, but I don't know for sure.

The downey kit is pricey and if you can scrounge parts then it can be done quite a bit cheaper. If you can find a 4 bbl manifold you can get a cheap TBI adapter for it. The Downey kit is convenient though, then you don't have to find the right pump and sensors to fit.