What did you do to your truck today??

[Snarl95]

New headlight assemblies.

[Just call me Sean]

Changed this again on the '99.

[Boog]

I replaced all the bulbs in the gauge cluster in my '91. It was hard to see the gauges at night so after 30 years I figured it was due some new bulbs. Didn't help a dern bit!
So I replaced the old fan clutch with a new one. It no longer sounds like an airplane.

[Just call me Sean]

I picked up some dip switches so I can modify some VSSBs to correct my speedometer.

[Just call me Sean]

Desoldered the jumpers and the holes without jumpers, except for the center two that don't get changed. Soldered in the switches and set them the same as my van. Now instead of the speedometer showing 60 at 65 it now shows 66 at 65. Close enough for me, I can adjust it more later if I feel like it. And bonus, now I will get better gas mileage.

[Just call me Sean]

Today I learned that short bed trucks have different rear bumper brackets than long bed trucks.

[Boog]

Hmm. Could it be a difference between fleetside 1/2 and 3/4 ton trucks? The brackets are different in the LMC catalog but don't mention short or long bed.
That's just LMC so others may offer something else.

[Just call me Sean]

On the long bed the bracket has a nut welded to the forward most hole and the same size bolt as the rest of the bracket bolts. On the short bed the forward most hole is smaller with no welded nut because that smaller bolt also goes through the leaf spring hanger.

[Just call me Sean]

Changed the ICM on the '99. That's $100 part. Funny thing, I didn't unhook the battery when I changed it. After I started it I checked for codes and the computer said "hey, somebody unplugged the ICM."

[Just call me Sean]

The 99 is kicking my ass. The new ICM was bad, that's why I got that code. Old one back on no codes. Doesn't want to start sometimes. Sometimes runs great sometimes misses. Hard to diagnose when it's only intermittent, but it's not starting more often now. Haven't driven it in a month but try to start it every day. Fuel pressure is good, and I can smell the gas. Getting spark, checked with a timing light. Flashes while cranking while not starting. I can't remember if I inspected the plugs, I know I did on the 93, so I'm doing that next possibly again.

[Just call me Sean]

Tried fixing the 99 again today. When it starts it runs good, runs normal. When it doesn't start right the engine runs backwards, yes it runs backwards. Figured that out today. I killed the starter and the battery trying to figure it out, watching the engine run backwards. I don't know what to do now. Anyone have any ideas?

[Boog]

A fuel injected gas engine running backwards. Bout has to be timing/ecm related. Good luck with that one.

[Gunner41]

Trying to rebuild the Hydroboost. Problem is that according to the info I found it says that it is missing the check ball and pin? Im now in the lost world of Hydroboost and will now need to research it. Ugh

[Just call me Sean]

Originally Posted by Boog

A fuel injected gas engine running backwards. Bout has to be timing/ecm related. Good luck with that one.

I've searched it, it has happened to others, but haven't found a solution. I can't figure out why one moment it runs great and the next it's going backwards. Shouldn't be mechanical, has to be electrical.

[Boog]

I remembered you posted this in one of my threads:

{I had to ground my computer to the battery, and I had to ground the computer case to the battery.}

That is not normal so it about has to be related to your Burb's run back issue doesn't it? Bad grounds do cause strange issues at times.
Also, what was done last to the truck before that run back issue started?
Back tracking here.

[Just call me Sean]

The added ground was my 93, the 99 is running backwards. I was working on random misfiring which makes me think it's the same problem but worse now. I changed the distributor cap and rotor, plug wires, removed the distributor and inspected the gear. The distributor is in correct, otherwise it wouldn't run perfect one second then backwards the next. No cam/crank correlation codes either, no codes at all.

[Boog]

I'm sorry. I didn't know you were dealing with two vehicles.
How long will the 99 run backwards? When the engine runs backwards, so does the oil pump. Could damage bearings and such.

[Just call me Sean]

When it runs backwards fast it will go for about two seconds or so. When it runs slow it will go longer at about one revolution per second.

I'll have to change the starter first, but I guess next I'll unplug the crankshaft sensor and see what it does. Unplug some sensors one at a time and try to force a code.

[Just call me Sean]

Changed the starter. Fired right up, backwards. Unplugged the crankshaft sensor, no start and got a crankshaft sensor code.

[Just call me Sean]

Removed the crankshaft sensor and it has been contacting the gear. Installed it loose and it still ran backwards. Tightened it back down. Removed the cap and rotor to inspect them and make sure the distributor was still aligned. It is. Reinstalled and fired right up, running good. I did bend the rotor tab up to make better contact with the cap, but I don't think that is the problem. I think it just decided to run again.

[Boog]

Something is advancing the timing too far causing the engine to kick back which is hard on starters too. Possibly a pinched or partially broken wire going to the distributor or ecm? Have you had a scanner hooked up to watch live data? Faulty computer or corroded wires there?
I once had a start/no start/shut off while driving issue on a Blazer. For months I fooled with that one. Finally I started grabbing wire harnesses under the hood and moving them around then I found the issue. The wires going into the side of the distributor had been pinched and when I lifted up on the harness it shut the engine off. No start. I pushed them back down and it started again. Ahah. Bad harness and could not see damage from the outside.

[Just call me Sean]

I think it's fixed now. I took it for a drive and it ran better than it used to. Whenever I don't get codes it's usually a tune up/routine maintenance type of problem. I got out the old rotor and could tell the bend that I straightened on the new one was pretty severe, about a quarter inch. It must have left such a large gap that the spark took longer to jump the gap and fired the cylinders at least one off, but everything the computer sees was functioning correctly so no codes. So, brand new Duralast rotor is junk. It has started every time since, but I don't quite trust it yet because it has fooled me before. I'm going to order an AC Delco or Delphi rotor to swap on. I don't know how much better it will be but it is a different design than the Duralast one.

[Just call me Sean]

I tried to start the 99 and it went backwards again. I didn't get another new rotor yet so I put the old one I saved back on. It started right up.

[Boog]

I know you've replaced the dist cap already but what are the chances this crab cap is randomly leaking spark? Use a spray bottle of water over the dist and wires?
Did I mention I hate electrical issues?

[Just call me Sean]

Originally Posted by Boog

I know you've replaced the dist cap already but what are the chances this crab cap is randomly leaking spark? Use a spray bottle of water over the dist and wires?
Did I mention I hate electrical issues?

It's possible, the cap may be the same crap quality. I don't even know which would be good quality, I hear they all suck. The wires had burn marks all over, and they were changed right before I got the truck. I'm going to order the AC Delco rotor and see what happens, get the AC Delco cap if it keeps doing it, and if it still does it I'll get the whole distributor since it seems it starts after I touch it. Wiggling the wires to it and thumping it while running doesn't make it stall though.