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TPI still doesn't run... Bit puzzling, anyone have any ideas?

Russell

Russell

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Hey guys!

I'm still trying to diagnose the problem with my TPI so I can get it running to re-sell.

Basically, it seems to be flooding itself out, so I pulled all the plugs, cranked it over half a dozen times, left it for a few hours, cranked it again etc to clear all the gas out. I then took my torch, and stuck it in the end of each of the plug holes and repeated the whole procedure until I didn't get any more gas igniting from the cylinders. I then cleaned my plugs up by running them in my stepside for 30 minutes or so. I unplugged my fuel pump, and made sure that there was no fuel pressure on the rail so the injectors wouldn't do any more than maybe dribble a bit when they pulsed while cranking. I then shot a small squirt of gas into the intake, and hit the key. I'd have expected it to at least sputter a bit, but didn't get anything from the engine.

I seem to have a hot blue spark off all of my wires, but my engine doesn't even try to fire, even with me just spoon feeding the intake to make sure that it wasn't flooded... I have good compression in all my cylinders, within a point or two of eachother, and I'm fairly sure the air in my shop is combustible, lol

Any ideas of what might be wrong? I'm going to try the small cap HEI from the Stepside's TBI setup tommorow, and see if it helps any...
 
I wouldn't spend time swapping parts yet. What does a test light on the injector leads tell you? (And no, you can NOT run one end to ground...one wire to each terminal on the connector)

If you don't have a pulse, the ECM is not "seeing" the engine rotating, or the ECM is fried, and you get no fuel. (doesn't sound like the problem, but do it anyway)

If you have a pulse, you aren't getting fuel, or you are getting too much.

Keep it simple, don't overthink it, at least not yet. :)

"Seems to be" flooding itself out isn't "it IS flooding". I mean we could go for temp sensor, fuel pump, fuel pressure regulator, bad injectors, and so on just because it won't start, but knock the basics out first. Even if you have already, do it again and make sure you didn't miss something.

I'm a little confused as to how pulling the plugs and cranking it clears the fuel...it will pump fuel as long as you crank it unless the ECM is not getting the pulse from the distributor or there is no fuel at the rails, or the injectors are unplugged and actually staying shut.
 
Ok, guess I better explain what I did so far, lol

Basically, 2 - 3 months ago the truck started running worse and worse, eventually letting off a backfire, and refusing to start again. Upon pulling the plugs, I discovered they were covered with carbon, and soaked in gas. Just cranking the engine with the fuel pump unplugged caused visible gas droplets to be shot out of each of the piston holes.

I got frustrated with the thing, and just parked it.

Fast forward to yesterday, when I decided to make an attempt to get it up and running again. First things first, I re-set my timing by setting the engine to TDC, turning the ignition on, and roating the dizzy till it sparked piston one. That should have gotten me fairly close to 0 degrees, which should be close enough to fire on. I then tried to fire the truck up, but got absolutely nothing. So, I pulled a plug to get it out, and it was totally soaked in gas again.

That lead me to think that either I was getting too much fuel, or the spark was too weak to ignite the fuel. So, I tested my coil, and found it was pretty weak. I grabbed the coil out of my K5 (TPI is using a big cap HEI at the moment), and found that I had a nice hot blue spark on all 8 cylinders then.

I tried starting the truck again, but again got absolutely nothing. I then gave up on the truck for the night, and came inside.

Today I went out, unloaded the cab from the back of the truck, and pushed it into my shop. I figured that since it seemed to have a good strong spark, and was definitely putting fuel in, that it was putting way too much fuel in, and that maybe my 24 lbs injectors were too big for the stock 350. So I went and grabbed a set of known good 22lb injectors from a buddy's currently torn down TPI 350, and installed them. I also checked the IAT, CTS, and TPS with my scanner to make sure they were all around what they should be. I tried firing the truck up with the 22 lb injectors, and just wound up with wet plugs again.

So, I pulled the plugs from the engine, and unplugged the fuel pump. I cranked the engine a couple times to let the injectors release any fuel they may have had, then got to work on clearing the "flood". I did this by taking my butane torch, and sticking the end in each plug hole, allowing the fuel inside to flare up, and burn. I then went and cranked the engine a few times to mix up any more fuel there was, burnt it, and repeated the procedure until I didn't get any more flares from the cylinder holes, convincing me that the flooding was cleared. I then cleaned my plugs up, sanding the electrode to scuff the carbon off, and stabbed it all back together. I then cranked the engine with the fuel pump unhooked to see if I got any popping. When I didn't, I got a turkey baster I keep in my shop, and shot some gas in my intake, which should have been plenty enough to fire on, but not enough to flood on. When I hit the key, I again didn't even get so much as a pop out of it.

This all leads me to believe that for some reason my dizzy isn't sending any spark through the plugs, and that it is just pumping fuel straight in. So, I'm going to try switching the dizzy from my TBI truck over, and putting the dizzy from the TPI into the TBI truck, to see if I can get either or to run. That will confirm the operation of either distributor, and prove that it is a fuel delivery issue.

My fuel system has 40 PSI of pressure when the pump is plugged in, and the injectors pulse as they should when you crank the engine. Electrically speaking, the engine should be fine. It actually ran quite well in the past... If I find that the fuel delivery system, and the ignition systems are both good, then the only thing left to be bad is my ECM, or my memcal.
 
Your system running a cold start injector?

Another thing I can think of. Can't recall the year of your setup though.

If you've got pulse, then the ECM is seeing the coil fire, so as long as timing is even close, it should run if it's got the right amound of fuel.

http://coloradok5.com/forums/showthread.php?t=141717&highlight=troubleshooting

You've pretty much already done the crank no run test, but I'm curious if your scanner "passes" the "is RPM indicated during cranking?" test. Mine failed that with the bad ECM's, but I didn't re-test when I got a good ECM.

Check out the Chevythunder page, they've got the hard start page, but it references the cold start, if you don't have it, I'm sure it's off.

If you remember back when I broke a stud on my motor, I had weird fuel fouling issues, you didn't wipe a cam lobe or something did you?
 
Its quite possible the cam wiped a lobe out, but I am getting fuel into the cylinders, so the valves gotta be opening at least a little bit... I'm going to hook my scanner up, and go through all my grounds one more time this afternoon yet...
 
Did you have ANY dry cylinders?

It's a long shot, but my runner filled up with fuel, which spilled into the plenum and force fed all the other cylinders extra, when my intake valve stud snapped.

It also pulled oil past the rings and smoked pretty good, especially with the overly rich mixture.
 
Dunno what kind of ground issue you'd have, your stuff is obviously grounded if the injectors and sensors all read correctly.
 
yeah, not likely to be a grounding issue with everything reading properly, but I figured it wouldn't hurt to check anyways, since the grounds always seem to wind up being the problem... I did find a loose one on the driver's side head, but it shouldn't matter too much, I've got all the grounds, less sensor grounds, connected together, then they all spider across the engine. One to the intake, one to each head, and one to the exhaust manifold with the 02 sensor in it.

I didn't notice a dry cylinder anywhere, but that was definitely a good thought!

I got my dizzies about half way switched out. Rather than cutting my TPI harness up again to re-wire for the new style small cap dizzy, I hard wired both trucks to work with the big cap dizzy, then made a few adapters for going to the small cap HEI. I got everything finished up except for the coil power supply adapter, since I broke my old connector, doh!

I'll let you know if it roars to life tommorow or not...

Once it runs, I can sell the setup, then drop my TBI setup in to run for the summer, and switch over to the 5.3L next fall once I've got all the parts collected together.
 
Hey,

Unfortunately, I have nothing of value to add, but I did want to jump in to say I am reading your thread anxiously awaiting your success...call this a moral support post. Good luck.
 
I appreciate it Rob!

This swap has been almost 3 years in the making now, and just as soon as I get it running, I'm getting rid of it ASAP, lol
 
Well, I did a bunch of re-wiring to move wires that could potentially be affected the ignition system and that were placed kinda poorly, then installed a few connectors to make the EFI harness totally removeable from the truck's engine harness. The wiring looks 10x cleaner now, and there shouldn't be any concerns of electrical interference.

Once I got that done, I installed the small cap HEI from the 77's TBI setup, and spent some time making a pair of adapters so I didn't have to change any wiring to install the small cap, incase it made no difference. However, I hit the key, and it immediately started sputtering, a very good sign!

It is cold out today, so tommorow when it is warmer I'll shove it out of the shop, and get it tuned up a bunch. Also gonna figure out something with my fuel filler neck, so I can get some gas into the ol' girl.
 
Trust me Rob, I started my swap at least a year and a half, if not two years before you, and your truck is still major inspiration for me!

Mine woulda gone a lot easier if I didn't have to make a custom wiring harness from scratch using junkyard connectors, and peice basically all the electrical together less the TPS... Heck, my throttle body was missing both the coolant passage housing, and the top plate :P

Gonna be so nice if I can get it to run nicely tommorow... Maybe even try forcing open loop, and seeing if I can manually tune it to idle a bit better, LOL

If it runs reasonably well, maybe I'll drop the cash on a camshaft for the truck, and run the TPI for the summer, get the thing registered and insured, get some time behind the wheel so I know it is ready to haul quads this summer :D
 
It's a nice feeling to have a truck up and running after major work, that's for sure.

Still don't trust mine for long trips though...it has to earn my trust again. :)
 
Well, it runs better than it ever has before. I'd have no problem putting this thing on the street, less one problem that reared it's ugly head.

When I started this morning, my driveway was dry, so was my underchassis, now its all covered in oil :(

No idea where its leaking from, but its a real bad leak...
 
If it's not one thing, it's another!

Mine's dribbling a bit of oil (one piece pan gasket too!) but last time I changed the oil I threw in 4 quarts (5 or 6 quart pan) before checking the dipstick. When I did check it, way over full!

So I drained some out, but it's still over full. I'm hoping it's putting the oil level up high just high enough that the rear main seal has oil that's right against it thus the leak. Maybe yours is this easy. :)

Oil cooler line leaking? Mech. fuel pump plate?
 
I also am noticing low oil pressure, so I think maybe I might have ruptured my oil pressure gauge line while I was dinking around back there mounting my ignition coil, lol


Front might be the mech fuel pump, which I left on there as a blockoff. I'll replace both tommorow.

Still debating on if I take the TPI and re-sell it, or if I put the TBI heads on, and get a TPI friendly camshaft then drive the thing as is...

It has simply insane torque, lights em up at will, but really seems to lack top end power, I think that is mostly a tuning issue. Idle is still fairly rough too, think it is on the lean side, as I get the occasional pop out of the intake (timing is right, and I checked my plug wires a billion times over, lol)

We'll see if I can sell the TPI or not, or if I sell the K5. If the K5 goes first, I'll get my camshaft, and hang onto the TPI, if the TPI goes first, then I'll put that money towards getting the 5.3L mated to my NV4500, lol
 
This is hilaarious...After my first drive out, I noticed that my tranny was dripping gear oil. It has never dripped, not once, but somehow, putting in a new engine (and comp style engine mounts...a ha, probably the culprit) has made my tranny leak...So can we start a cool club like "The leaky TPI guys?
 
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