89 TBI 350 stumbling around cruise

[jim_in_dorris]

Are you referring to my problem, it's not clear given the quote above your post.

I haven't been able to install the new grounds yet (owing to work and weather), but I have fabricated a few of them. One thing I did notice is when I relocated the sensor grounds from the thermostat bolt to the manifold bolt nearby, apparently I didn't run a ground from there off to the battery/body. So that is a HIGHLY suspect potential cause of this issue. Some would say relocating the grounds form the thermostat bolt is the issue you'll just never convince me a bolt threaded into an aluminum manifold is any better a ground than using a bolt going into the iron head (which, if we are being picky, the manifold was bolted into, so it should actually be a BETTER ground as it cuts down on the chain of grounds to get back to the negative terminal on the battery. ... well, you know, if I'd actually run that darn wire ;) )

This is clearly going to be the FIRST ground I improve. I built a 2-GA cable out of welding cable with a copper lug hammer-crimped to it and soldered (honestly, solder would be just fine on its own, and I've built many a cable that way) with marine-grade heatshrink over 3M electrical tape to seal against the weather.

Doing this on my phone, only gives me the option of reply with quote. I also replaced all the grounds and power with 2 GA wire fixed my low voltage problems, but not the stumble. I only found the problem after a backfire caused a small fire in the engine compartment and I decided to tear down the motor and freshen it up. Both heads went to the machine shop for a valve job, and both were cracked. Not say that is your problem, but it is a possibility

[89S10_Project]

I hear you. I am not backfiring through the intake, but the exhaust. This seems to me that it is caused by excess fuel in the exhaust , which gets hot and occasionally explodes.

[jim_in_dorris]

I hear you. I am not backfiring through the intake, but the exhaust. This seems to me that it is caused by excess fuel in the exhaust , which gets hot and occasionally explodes.

While trying to find replacement heads, I looked at a lot of 193 heads. Out of the 8 I looked at 7 were cracked. A burned exhaust valve is common on these heads. Have you done a compression test.

[89S10_Project]

Well, I apparently had replaced the grounds in the past, with 10GA to each head, to a stud on the passenger fenderwell used as a ground terminal (yes, very hack, I agree, but all I had at the time). I added 2GA grounds to each head, just forward of the intake. ran them to a buss bar, found here: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Ran a jumper from the battery to the buss bar as well. Ran another from the firewall under the coil bolt, to the driver's side (also where all the sensors get their ground).

Added a red version of the above, to the driver's side firewall. Ran all my aux circuits to it, and it's fed by a piece of 2GA. Replaced the alternator wire (factory, approx 10GA) with a piece of 2GA. All terminals are hammer-crimped and soldered, with marine heatshrink over them.

It's too soon to tell, but she sure seemed to run better this morning. I doubt this was all of the problem, but it may have been some.

I also note a new development on my gauges. The oil pressure gauge used to read fine on cold start, then go to nothing on hot idle. I'd verifed with a mechanical gauge that it was fine so I wasn't too excited. Now, with key on and not running, it shows pegged at 60PSI. running, same thing. Drops to nil at key off (as it should). I think it's time to pull the panel and check my grounds on it. I likely have some issues there, at the very least I need to replace bulbs. That may well be part of the issue, actually- absent groundplane due to the bulbs being blown. I have LEDs to replace them, just haven't had time to suss it out.

My neighbor has a 97 Tacoma he wants to sell, for $2000. The truck books out somewhere around 4G. Done! 22MPG with cold air, and a parts runner (bed) so I can get some of the unwiledly crap I've been needing to get (engine for the jeep) as well as household stuff I need to run to the dump taken care of. It's a no-brainer.