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I haven't completely given up on this yet

85 Jimmy

85 Jimmy

Sheepdog
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But I'm close...

If you don't know, I'm talking about the TPI in my truck.

I just changed the sending unit and fuel filter in my truck. In the process, I ran the truck out of gas in my driveway to make sure the tank was empty. So I get everything all back together, put 10 gallons of fresh gas in it, and now it won't start.

I primed the system by cycling the pump a few times, and when cranking it stumbles like it's trying to start, but won't fire up. It also does the same thing when I spray it with starter fluid. I checked the injectors with a noid light and the are getting a pulse. I'm about to go out and check the fuel pressure.

To me it seems like fouled plugs, but how do I check the spray on injectors or if they're completely clogged?
 
It was fouled plugs... Now to see if it's still backfiring on deceleration
 
And it still pops and backfires on deceleration...

Here's my other thread on it, but since there aren't any codes now, I'll continue in this thread.

http://coloradok5.com/forums/showthread.php?t=319625

One thing that I've noticed is when I get on the throttle, it doesn't respond right away. Sometimes if I get on it, then back off alittle, it will start to accelerate the way it should. It just overall feels like a turd that doesn't want to move.
 
I didn't go to the other thread, I probably posted there too lol.

Popping on deceleration is fuel going out the pipes. That's my problem now, for some reason decel fuel cutoff isn't working, and its dumping raw fuel, leading to nasty fumes and an unwillingness to compression brake on my part. I know in my case it's something to do with the programming. In your case, could be a few things.

You certain the timing is right, no exhaust leaks in front of the O2, spark is good to all cylinders, compression is good on all of them as well? You've unplugged each connector with it running to make sure you don't have a dead cylinder? Pretty easy to do, saves from getting shocked like pulling plug wires. Without spending a bunch more time thinking it through, I might even try pulling each injector connector and seeing if it affects the decel pop, to eliminate injector problems.

Your CEL is working properly, just no codes? Datalogs?

I don't think another EFI system is the answer, no guarantee it works right, and if there is a problem, diagnostics are roughly going to be the same. All the EFI systems from TPI onward are pretty much the same (minus coil on plug, crank sensors, etc). Obviously the LS series is a better engine in general, so from that standpoint it's worth it, but working properly my first hand opinion is that the TPI setup makes pretty good power and runs good, when working right.
 
The other thread is about the code 44. it was pretty much you and I trying to get this thing figured out, with a few other people giving their opinion.

I don't have any exhaust leaks anywhere, and I'm pretty sure I CEL is working correctly, I get the code 12 or 13 (I forget which one) saying that it at least thinks it's working.

I haven't checked compression, nor have I checked for a dead cylinder. I'll try to look at that this weekend.

Would this also make the truck feel like it's gutless and has no power on acceleration? It does run super rich, at least it smells like it when it's just idling in the driveway. Could it be a fouled out or inop heated O2 sensor? Also, this isn't normally a little rumble on decel, it's loud backfires, but not every time, just if I don't slowly roll off the throttle. Not sure if that makes a difference trying to figure it out.

One thing I thought about throughout the time, I have 24 lb injectors in it right now, but I don't remember if i got the PROM burned for 22 lb injectors or 24 lb injectors. I had it done at street and performance, but the last time I talked to them they said they don't have a record of me buying anything from them.
 
O2 has nothing to do with "power". It isn't used to calc fuel when you accelerate. It shouldn't be used on decel either, as fuel should be cut completely off. But in a datalog on decel the O2 should show dead lean, and obviously constantly rich under heavier throttle.

Dead cylinder would certainly cause a lack of power, but so would knock, since it will retard timing. You'd have to datalog to see if that was going on. I suppose depending on the problem, even a valve problem could be a reason, you can't tell a flat cam lobe (or broken rocker stud lol) on a compression test. Thing with TPI is that if you have an intake valve that doesn't open, the plenum will eventually fill with fuel and you'll know it. Not to mention the exhaust will start to smoke since the intake stroke will be what is pulled through the rings, which will contain some oil. But a worn cam lobe could be an issue, and you'd not see if with compression. I wouldn't bank on that, just another potential issue since you aren't dealing with a CEL indicating a hard fault.

TPI IME will idle very well even on 7 cylinders. If something else is affecting idle (vac leak, exhaust leak, fuel pressure issue, etc) it's even more difficult to feel when you disconnect a cylinder.
 
I don't see the answer to this so I will ask.

Have you verified fuel pressure? New pump new pressure new volume.... Is the regulator working correctly? Is it getting vacuum reference?

If you are blowing out plugs then you are way fat, no spark or a dead cyl.
 
Fuel pressure was 42 psi when I checked it, and the regulator does have vacuum to it.
 
85 Jimmy said:
Fuel pressure was 42 psi when I checked it, and the regulator does have vacuum to it.
Click to expand...

K, can you test again and see what pressure is with car running vacuum hooked up to reg and vacuum unhooked. Just verifying the reg is working.
 
If all that checks out then every sensor needs to be tested/verified on a scanner.

Just had a TPI come in running rough, rough idle, hesitating.... Turned out the TPS was bad. Still in range to not throw a code but stuck on a voltage. New TPS and its a screamer again.
 
There used to also be a free program called WinALDL that I used on my TPI.
I haven't looked to see if it's still available....but you will need the cable to connect.......IIRC it works fairly well for checking sensors.

Another check would also be for chaffed/shorted wires to a sensor.....could be intermittently connecting/losing connection?.....just a thought...

They can be a PITA but.......don't give up..............they're really not too complicated...and there is the possibility it's a mechanical issue....?
Good Luck with it.....!
 
I'm going to try some more diagnostics this weekend. I had a huge test today I had to study for, and I work this weekend.

One thing I noticed when I checked the plugs was that cylinders 1,3,5,7,6, and 8 were soaking wet with fuel. While cylinders 2 and 4 where dry, but black like the rest of them.

I guess the first thing I'll do is while it's running, disconnect each injector to see if there's a change. I'll also check fuel pressure with and without vacuum.
 
Totally possible then that you are getting too much fuel from a faulty O2/bad O2 reading, map or maf reading, bad ignition, or regulator that's not working correctly.

Other causes as well, but if that many plugs are wet, it's not likely to be a mechanical issue. One dead cylinder would be fairly believable from a bad cam lobe, compression, etc...that many not so much.
 
Hmm. There used to be a guy on gearhead-efi making cables and selling them, which the profits were then used to help the site, but I can't find a link now.

You don't want the 160 baud cable. You want the 8192 cable, and you will want to use Tunerpro RT. WinALDL is ok, but your ECM is far faster than the ECM's WinALDL and it's cables are designed for, so you lose some of what's going on between data updates. Tunerpro is "free" (please donate if you like it, Mark Mansur made it all himself, that program is him) and very full of features, so I recommend it far and away over WinALDL.
 
There you go....................it was years ago when I put the TPI in my Jeep.........:dunno:.........never had an issue
with it besides the vacuum leak I posted in the other thread........
 
Yeah, WinALDL was it for quite awhile, Tunerpro is fairly modern comparatively. WinALDL has been around for ages.
 
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