No towing power and no overdrive?

[Yknot]

Thanks in advance!

1994 Suburban
Remote mounted FSD
Kennedy High Flow Water Pump
IP and Fuel lift pump replaced in '05

Yesterday I was unable to tow my boat out of the water! Usually, it has no problems what-so-ever but yesterday it seem like I was using my honda civic to two it up the ramp!

The funny thing is that I was able to tow the boat (3 tons) over the hill and to the dock. Though I did notice that the suburban had a harder than usual time pulling out of my parking space at the boat yard earlier that morning (I had to go over a piece of lumber at dead stop). I also had a hard time pulling the empty trailer up the ramp after launching.

A possibly related recent problem is that it now has problems going into overdrive unless I cycle my engine (at highway speeds....)

The only codes I got was a 12. I think I read it right ...

blink pause blink blink long pause
blink pause blink blink long pause
....

I'v got trans fluid and it does not look burnt.

Any help will be appreciated.

Thanks,

yknot

[sailun]

Well, if you hadn't said you had trouble with the EMPTY trailer, I woulda said check the bilges.

[a5150nut]

Code 12 says the computer is working and no codes stored. There were no other codes after that?

I would start by checking ALL ground connections, fuel supply, and air supply.

[Yknot]

Okay, I'll check my grounds and report back. It'll next weekend before I can get to it. Could it be anything else?

Thanks,

Yknot

[Robyn]

If there are no codes and things seem ok with the way the engine runs, No smoke or other issues does the engine seem to rev a lot more like its trying but just cant go??

It is possible that you lost the sprag in one of the stators.

The 4L80 has two stators in the convertor.
If the stator goes away you wont get torque multiplication and the thing will become a real slug.

My dually with a 400 did this on the way back from LA and I was loaded.
I was able to get it home but luckily I had made the Vine before it went south.

One way to tell is to have someone else powerbrake the thing in drive while you listen to it.
If you hear a cavitation noise coming from the tranny area its a good bet the converter went away.

I would drop the pan ans see if you have a bunch of crud in there.
Metal junk will usually be evident and or possibly some black plastic looking stuff.

This type of a failure will not usually give a burnt smell to the fluid.

Give this a check and report back.

Good luck

Robyn

[Yknot]

If there are no codes and things seem ok with the way the engine runs, No smoke or other issues does the engine seem to rev a lot more like its trying but just cant go??

It is possible that you lost the sprag in one of the stators.

The 4L80 has two stators in the convertor.
If the stator goes away you wont get torque multiplication and the thing will become a real slug.

My dually with a 400 did this on the way back from LA and I was loaded.
I was able to get it home but luckily I had made the Vine before it went south.

One way to tell is to have someone else powerbrake the thing in drive while you listen to it.
If you hear a cavitation noise coming from the tranny area its a good bet the converter went away.

I would drop the pan ans see if you have a bunch of crud in there.
Metal junk will usually be evident and or possibly some black plastic looking stuff.

This type of a failure will not usually give a burnt smell to the fluid.

Give this a check and report back.

Good luck

Robyn

Besides O/D not kicking in it runs good. I'll take a look in the pan and do the powerbreak test and report back.

Thanks for the advice.

Yknot

[Yknot]

Here more information that may be related to my problems.....

I found out my fuel lift pump was not working so I went about replacing it today. In doing so, I put the front wheels of my sub on portable ramps i just bought at Kragens. As it turns out, the new pump still does not work so it must be an electrical issue somewhere else, perhaps grounding issues?

Here is the intersting part, in this position similar to being on a boat ramp, my IP pump was not strong enough to pull enough fuel to start the engine (at least after quite of few cranks....)! Now, I'm wondering if this would also cause loss of towing power? Seems reasonalble to me. What do you think?


Still need to check the ground and other basic trouble shooting.

Yknot

[a5150nut]

Is the pump making noise? Maybe an air leak in the suction line between tank and pump?

[bbtlr3]

Check the Oil Pressure switch. I had a shop tell my wife that the lift pump was bad on our 94 Burb. I got back from Iraq and jumped the connector on the OPS and the pump fired right up. Replaced the switch and all worked good. This seems to be a common problem and hard starts seem to be one symptom of a non-functioning LP. Hope this helps

[Yknot]

Check the Oil Pressure switch. I had a shop tell my wife that the lift pump was bad on our 94 Burb. I got back from Iraq and jumped the connector on the OPS and the pump fired right up. Replaced the switch and all worked good. This seems to be a common problem and hard starts seem to be one symptom of a non-functioning LP. Hope this helps

Yup. Thanks. The OPS is on the blink again (was changed 1 year ago). I jumped the the switch and the LP came on. I've ordered the Kennedy Lift Pump Control Harness to see if this will solve my issue without changing the OPS (which is a PITA to change!).

I hope this solves my towing and over drive issue!

I post results.

Yknot

[Yknot]

Here is an update on my situation.

I put in a new OPS and my fuel lift pump works fine now but I still have no overdrive and pittiful low end pulling power when trailering my 3 ton boat+trailer. I'm going fishing anyway this weekend (gotta land my first salmon of the season!) and think my 4L will pull the rig up the ramp even with this issue. I tried 4H the last time and forgot to put it in 4L! :(

I also drilled two holes on the round plastic container on my APP and sprayed it with a generous amount of electronic contact cleaner. I also sprayed the connection to the APP for good measure. That had no effect.

I think I remember reading in another thread that there are electrical connections on the transmission itself that may need cleaning and or replacement as part of preventive maintenance? Can anyone clarify what this part is so I can be somewhat intelligent when I talk to the local parts shop?

I still need to check the ground next to the starter, I'll probably to that on Sunday. Also, there is no cavitation noise coming from the tranny when I powerbreak. At least I did not hear anything strange when doing this myself while holding the break, reving the engine, and sticking my head the open door

[Yknot]

Here's the wrap-up on my situation.... I replaced the standard ground cable with a heavy duty battery cable, I drilled two holes on my APP and shot it with cleaner, I reset the electronics by disconnecting the battery. Now all is well! The tranny shifts and I have over drive!

Thanks for the help!

Derek

[PLUMMER]

WOW!........ nice post and updates. I had some very similar symptoms, with my 6.5 van. just at high speeds. I've already replaced my GC 2 years ago. guess its time for another. My LP also went just 3 weeks ago, blows 20A fuse and i replaced it again 120.00 later and truck was fine but now with a load its huffin. I made a post about it in the 6.5 tech 4rum.