Still troubleshooting TBI install--spark ?

Goldhawg · Jun 20, 2010

For those following my initial start up of the TBI, I was chasing a low vacuum issue, and was getting pretty close:
http://classicbroncos.com/forums/showthread.php?t=164037&page=2

when the engine wouldn't stay running after start up. Trying to chase down possible issues and while my timing light will flash indicating a spark going thru the wire, when I pulled a plug wire and stuck a spark plug in it, I'm getting no spark. I have an MSD pro billet dizzy, w/6A and blaster 2 coil. Is it possible to have a distributor issue that sends some signal thru the wire but not enough to fire a plug?

broncnaz · Jun 20, 2010

Might be a coil issue as if the dist and igintion box are sending a spark through the wire then all it has to do is be strong enough to jump the gap. Although the msd igintion box does control the amount of voltage/amps going to the coil so if its hooked up wrong or has something wrong with it you may not get enough juice from the coil.
You are grounding the spark plug right? It wont spark unless grounded.
Could also just be a bad plug.

Goldhawg · Jun 20, 2010

broncnaz said:
You are grounding the spark plug right? It wont spark unless grounded.

Dooh...no. just holding the plug in the wire and hoping not to shock the @#%$ out of my hand. And I did try two plugs, so guess its just not grounded. Can you just have the threaded area of the plug resting against the cast iron head to ground and watch for a spark?

Thx!

DirtDonk · Jun 20, 2010

Yep. That's how it's done. I always like to lay the plug as far away from delicate electronics as possible though, so if you have a module inside your distributor, don't lay the test-plug next to the distributor. Same thing for a Duraspark. Although they seem pretty resistant to this kind of stuff, I don't lay test-plugs on their cases while looking for sparks either.

Paul

broncnaz · Jun 20, 2010

If you get a shock you'll know how good the igintion is working;D

Goldhawg · Jun 20, 2010

Well, I did ground it and had spark. Found online that the coil needed to be mounted vertically and I mounted it horizontally for this conversion. So I ran out and bought a new blaster 2 coil, but still no joy. If the coil did fail, could it have also damaged anything else in the ignition system?

Thx!

broncnaz · Jun 20, 2010

Well if you have spark then I would say the system is working. While its probably better to mount it vertically I dont think mounting it horizontal makes much a differance unless it started leaking oil. But it is better to mount vertically to prevent premature oil leakage. It shouldnt damage anything else and again if your getting spark then thats a good sign that the igintion is working. Now timing could just be off some how maybe the roll pin in the gear has braken and the gear slipped or you have a fuel issue like no fuel when cranking.

Goldhawg · Jun 22, 2010

Well, continued troubleshooting tonite (last nite was anniversary #24, so to keep that streak going there was no car work).

Bottom line--no fuel pressure! I had checked previously w/friend who confirmed fuel was going out of injectors, but perhaps it was on its last legs. I had no pressure. Checked voltage @ pump and while it was pumping (1st 3 seconds) had a steady 12.3V. Pump made noise and was vibrating, including the output line as if it was pumping. But up @ the tbi unit I was never able to get more than 5 psi, even w/return line clamped off. Pulled the supply fuel line and turned key on and got a few dribbles of fuel, but not much else.

The fuel pump was mislabeled from factory (had to switch +/- connections to get fuel pumping in the first place). The way I have it mounted it is not below half a tank like Howell recommends (more like 2/3s) but I still have a completely full tank. Can't believe that would cause a pump failure.

So I guess I need to get another pump; Howell's are $135, then I'd have to wait for shipping, and I'm not too satisfied w/a pump that had electrodes mislabeled in the first place, and then may have failed. Any suggestions on pumps that I might be able to get locally in Albuquerque?

Pa PITT · Jun 22, 2010

I'm going to respond to this to move it back up and so I can show it to Running Buddy ....

broncnaz · Jun 22, 2010

Appears like it was one of my first suggestions about the poor idle.

Goldhawg · Jun 22, 2010

My problem is that fuel pressure is still hard to check. I bought a fitting for the back of the tbi that has the schrader valve off ebay but it interfered w/manifold. Had to go rent the autozone kit again that has an inline metal tube w/schrader valve that you can hook up a fuel gauge to. So when we saw fuel spraying, thought it was good.

Anyway, I'm somewhat encouraged cuz I think I can handle this fix.

broncnaz · Jun 22, 2010

Had the same issue with my neighbors truck it was spraying fuel at idle so I kinda discounted the fuel pump being the issue come to find out it just wasnt spraying enough. Changed out the fuel pump and all was good again. Wont say all was perfect as it is a TBI setup but it was running like it was supposed to.

robofig · Jun 23, 2010

Goldhawg said:
My problem is that fuel pressure is still hard to check. I bought a fitting for the back of the tbi that has the schrader valve off ebay but it interfered w/manifold. Had to go rent the autozone kit again that has an inline metal tube w/schrader valve that you can hook up a fuel gauge to. So when we saw fuel spraying, thought it was good.

Anyway, I'm somewhat encouraged cuz I think I can handle this fix.

Jegs sells a 1 1/2" fuel pressure gauge and a fitting to go into the pressure hose right behind the tbi. I think it is about 25 bucks.

Still troubleshooting TBI install--spark ?

Goldhawg

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broncnaz

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Goldhawg

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DirtDonk

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broncnaz

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Goldhawg

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broncnaz

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Goldhawg

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Pa PITT

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broncnaz

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Goldhawg

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broncnaz

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robofig

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