electrical? fuel? transmition? you tell me

[2Don2]

I am having an interesting problem with my 1994 3/4 ton gmc suburban.
After driving at any speed and cruising along. When I go from the fuel peddle to the brake (just touch the brake is all it takes) the rpm drops almost to a stall. Sometimes the reduction is great enough that it seems the pump tries to compensate and there is a burst of fuel to keep the rpms up, this sounds like a cough. According to my stock tac gage, when I take my foot off the fuel the rpm settles around 1000 - 1200 coasting at any speed above 30mph if I wait long enough the rpm will settle to 800 or so on its own but if I touch the break then the rpms drop immediately. If I take my foot off the break the rpms go back to 1000 or so.

It is an obvious thing and getting worse. I am also have a cold start problem that the gm dealer could not fix and now with this they have no idea where to start.

I have a new injector pump, glow plugs, glow controller, new engine, with DSG cooling upgrades, gages and pods, and other stuf too.

all this happened after the mods

I am so lost here please any ideas would be helpful

Don
cameron@yellowknife.com

[Turbine Doc]

looks like you might be having lift pump or fuel filter problems, check there 1st, open filter drain while at idle(brass valve, chrome tee handle center front of engine), if it stumbles/dies troubleshoot that, another possibility is APP module on accelerator pedal not commanding more fuel demand to IP.

[moondoggie]

Good Day!

[2Don2]

Thanks for the the ideas , keep them coming please.

The glow system was checked and fuel system, pumps, filters and injectors.All checked out

I just pulled some codes with the paperclip method and got a 13, engine shutoff solinoid circuit fault 46, malfunction indicator lamp (mil)circuit fault and 49,service throttle soon lamp circuit fault.

So does anyone know what these codes mean and could any of them be related to my rpm/break issue or cold start issue ?

I thought that if there was a code then an service engine light should come on?

Thanks again

Don

[CareyWeber]

[quote]Originally posted by moondoggie:
[b] Good Day!

[moondoggie]

Good Day!

The factory shop manual has troubleshooting flowcharts for each of these codes. I'm sorry to beg off, but I don't carry my shop manuals with me. If you haven't already bought one, you might want to get a factory shop manual for your truck, available from Helm (http://www.helminc.com) (Click in colored text.). I wouldn't own a vehicle without one myself.

Blessings!

Brian Johnson, #5044

[Barry Nave]

Do you have the late model fuel shutoff or still the early model.
Being a 94 the IP is probley up to date on the shut off.
Most always our trouble comes down to Elect.
Time to pull all contack wires,clean,dielect grease then trouble shout (out loud :D )