Hi, In my quest to find my start up stalling issue, I pulled the #4 fuse (at idle)and no difference in idle speed.I have checked a lot of other things, Vacuum hoses, throttle switch,air control valve,cleaned throttle body,AMM is working, new fuel filter,tune up etc...If I keep the tank full would the in-tank pump cause stalling? Or could it be my pressure regulator? Or both?

HELP!! Phil Stone, stalling '85 245GL 186K

A faulty check valve, located next to the fuel filter, allows the residual fuel to drain beck into the tank. Vreates a "vapor lock" type of starting (that is, a no starting) problem.

Hi Phil, your problem sounds similar to mine, if the car's been sitting for maybe 10 minutes, it can crank for a while, but will always start quick on a second try. And then it can stall just like that, but if I start driving, it will never stall.

Anyways, recently the intank pump and the pressure regulator were replaced, and the problem is a little better. It will start quick all the time now, but it still stalls sometimes, and sometimes the check engine light blinks on, but then goes out. I don't know what it is, but I suspect a vacuum leak.

I remember reading someone saying (about the plastic bellows between the AMM and the throttle body), that even if this piece looks good and you can't find any holes, sometimes just because it is old, the ends won't seal well anymore. I'm thinking about replacing mine.

Anyways, does your fuel pump make a lot of noise? Mine was noisy, and it turned out the intank pump wasn't working, AND the pressure regulator was making high fuel pressure. Those 2 things combined probably would have killed the fuel pump before long.

Hope this helps,

Greg

/// There is a small section of hose connecting the intank pump to its output line. This is the most likey failure given your milage. Since the pump runs with this failure you cannot change the output or test the pump by cutting off the juice to the pump. If this tube is the problem the gas intake for the main pump will now be several inches above the gas tank bottom. When the hose rots to the point of falling off the intank pump is no longer in the circuit. The gas supply will run out when the tank level drops below this point. Partial failure of the gas tube will complicate your diagnosis since some gas may be pumped even though the tube is damaged. Using a large container you can check the output from the tank. Remove the input line to the main pump and splice enough line to get you above the tank gas level. Test the intank pump. Gas will siphon when you disconnect the line until the gas level drops so the test must be above the tank level.

Siphon the tank down below the red line on the gas gauge before you begin. This method is safer and will eliminate the need to get above the tank level to test the pump.

Access is standard from a hatch in the trunk or under the rear deck. A wide blade such as a small garden hoe will remove the lock ring on the tank. There is usually a compression fitting in the return line above the axle so you do not have to cut it. Blow the area out with WD40 before you begin.