Rough Idle/Dies on Hot Startup '96 D1

stu454

stu454

Well-known member
Dec 15, 2004
5,407
61
Atlanta, GA
I've searched and not found anything listed with a resolution.

When my '96 non-evap D1 is cold, it's starts up fine. But when it is at operating temp, it'll often sputter and die upon start-up. The truck has 153000 miles, fresh plugs and wires, a new TPS and IACV.

No codes except the intermittent P0441 that might be an ECU glitch, per my previous searches.

Thanks.
 
stu454

stu454

Well-known member
Dec 15, 2004
5,407
61
Atlanta, GA
I swapped in a new pump when my old one died a few months ago.

I installed a new fuel filter a year or two ago.
 
stu454

stu454

Well-known member
Dec 15, 2004
5,407
61
Atlanta, GA
It may be something odd like that.

It started doing it intermittently and has since gotten worse. Even then, it won't do it every time.
 
stu454

stu454

Well-known member
Dec 15, 2004
5,407
61
Atlanta, GA
SGaynor said:
Clean the throttle body? got varnish in there?
Click to expand...

I feel like such a noob. I've scoured the RAVE and searched Dweb and cannot figure out the location of the throttle body. I haven't poked around under the hood yet; can you point me in the right direction?
 
SGaynor

SGaynor

Well-known member
Dec 6, 2006
7,148
162
52
Bristol, TN
Assuming no sarcasm..

It's what your plastic air intake tube connects to on the plenum. Pull the plastic tube off (undo the metal clamp) and look in there at the butterfly valve. If it's got crap there (varnish = a brownish film; black gunk/residue), hit it with carb/choke/throttle body cleaner and wipe down with paper towels. Open the butterfly valve (the round disk) by turning the throttle or pushing on the valve. Clean upper and lower halves.

I had a Suburban that built up varnish in there and would cause it to stall at idle occasionally (it was intermittent); no codes registered. Cleaning that cured it. My wife's "new" VW (160K mi), just recently stalled - the TB was full of black residue; no codes. Cleaned it an no issues in the last week.

Cleaning that is now part of my annual spring tune up/check up of my vehicles. YMMV

Edit: A sticky TB (or any other sensor) will cause the ECU to think something is wrong because it can't close the loop on what it thinks should be happening vs what it's sensors are telling it. Example is the VW above; it's EPC light came on initially, then went off - no codes. An internet search turned up a whole host of possible bad sensors/wiring (short) issues. But a couple of folks solved their issues with cleaning the TB (not that a failing sensor isn't the problem and/or intermittent).
 
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J

jkempf

Well-known member
Apr 8, 2009
63
0
Warren, Vermont
Hi,

Just went through this on another car that shares a part with the Rover. There is a fuel pressure regulator that trims the pressure according to the manifold pressure via a vacuum line. So there is a diaphragm in that thing that cracks and leaks and then you end up not getting the fuel trim and when it leaks it leaks fuel into the vacuum hose hooked to it which is hoovered up into the intake making it rich and more rich. It will cycle and cough on hot start and the plugs will be wet or fouled. Mine was actually hydrolocking due to fuel being dumped into one of the cylinders where the vacuum tap was on the manifold.

To check check fuel pressure and also pull the vacuum hose off and check if there is fuel, fuel smell, etc... on the vacuum side of the thing. The thing is located on the end of the fuel rail and the return to the tank is hooked to it. Small galvanized cylindrical thing with a couple fuel lines hooked to it and one vacuum hose.
 
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stu454

stu454

Well-known member
Dec 15, 2004
5,407
61
Atlanta, GA
Update: I swapped out the fuel pressure regulator yesterday. It appears that my hot start issue is better. I won't be satisfied that was the culprit until a I have a few more successful hot restarts, but it started right back up this morning after the drive to work. No sputtering or rough idle.

Thanks, guys.
 
pdxrovermech

pdxrovermech

Well-known member
Jul 3, 2009
1,807
57
Portland, OR
Just did the same thing last week to solve a customer's ongoing problem. It was only the second time in 15 years that i've ran into a bad regulator. He had the same symptoms. Car would always run fine, but after sitting for 5-10 minutes, on start up would stumble and die or just not start. fuel rail would be pressurize, but half full of air.
 
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