1993 240 Wagon.

Was throwing a bunch of codes got them all fixed, one was vacuum leak (split hose) other was a 2-3-1 code which ended up being an oxygen sensor. so new hose, new sensor and no more codes.

BUT

Engine still stalls. Will start up fine, runs fine, idles a little rough to start. Push the gas and hold and it stays pretty smooth with some small stutters, let off the gas goes to idle a little rough, step on gas it hesitates a little then goes.

Car will stall usually when idling and then pushing gas or will stall when left to idle for awhile.

No codes are being shown at all.

Fuel problem maybe? Fuel pump?

 

Sounds like the typical transfer pump. Check fuse #4 for transfer pump. If ok, remove the gas cap, have an assistant crank the engine while you listen for a buzzing or whir sound from the tank transfer pump. If the sound is consistent, the tank pump is probably good. If not, remove the flooring, and access the tank door for the transfer pump to test voltage.If you have 12 volts and no pump sound, there it is. If the pump is good, remove the pump and verify the connector hose is not split or broken.(I have had a good tank pump and bad hose). If everything still checks out, fuel pressure is needed.You should get about 43psi at the rail. Hope this is some help to you.

 

Will check those out tomorrow. For kicks I replaced the relay, only because it was the original one with 11/24/1992 on it, figured it couldn't hurt. (still same issue, but did seem to at least run a little better, could have been wishful thinking, still no codes after stalling).

I had someone turn the car on without starting it and didn't hear anything from the gas tank (no buzz or whir), so could that be it? or does it need to be cranked? Did check the fuse, it is good.

 

when you switch on the ignition, the pumps run for about 1 second then stop until you turn it over, then they run as long as its moving.

does that 1993 have Bosch LH or Regina/Rex EFI and ignition? the Regina system only uses one pump in the tank, no 'main' pump under the car.

 

It has the Bosch. There is pump/filter on the driver side rear, looks like its been there fir awhile. I have records for it from 2000-2011 and can't find any record of anything being done in the fuel area.

 

my 745T's tank pump was failing, the symptoms were lack of power at high throttle/RPM settings, and it was worse when there was less gas in the tank. the main pump under the car was noisy too. replacing the in tank pump, and the main pump quieted right now, and the car has power right up to the red line in any gear.

my daughter's 240's main pump was erratically failing, the symptoms were random no-starts when warm, 10 mins later, would start fine, and would run fine. finally, it wouldn't start at all. towed it to my mechanic's shop after hours, next day, it started fine for him, hah! but, he did some diagnostics, realized the pump was flakey (he tested there was power at the pump, and that in fact when he banged it, it started). so new pump and fuel filter, and that car runs great again.

note that these were just two specific different sets of symptoms, either pump can do different annoying and erratic things depending on its exact failure mode. note also that the fuel pump relay can cause similar problems, as can the wiring.

 

I replaced the relay just because of age. No difference.

I'm going to see what the fuel pressure is, I'm going to assume there is something goofy going on there.

The strange thing is, it will start up every time fine. But when it gets up to temp (only meaning when the temp gauge hits the middle), is when it stalls out after a couple minutes.

May hitting the fuel pump with a hammer will work? Can't hurt.

 

ahhhh. that sounds like a problem with the engine temperature sensor (ECT). there's two different ones, one has a single wire and is just for the needle on the dashboard, the other one has two wires, one wire goes to the ignition control unit (ICU) and the either to the injection control unit (ECU). the ECT is a pair of variable resistors, they are higher resistance when the engine is cold, and lower resistance when the engine is warm, the other end of each resistor goes to ground (engine block). I believe the wires are blue-red, but I could be wrong, thats from memory. either the sensor can go wonky, or the wiring can be sketchy (although this latter usually throws a code). these sensors are screwed into the side of the engine just below the intake manifold runners. they have been known to be in different positions on different model year cars, but I think the ECT is between the #1 and #2 intake tube. it has a rectangular connectoor that pulls straight out, as does the dashboard temp sensor. the other sensor is the anti-knock (if your car has one) and is flat and has the wires coming out at an angle


see this (written for the very similar 740/940 cars) http://www.swedishbricks.net/700900F...eSensors1.html that discusses this.

you can measure the resistance of this sensor to ground when its unplugged with the engine cold and hot, and you should see values similar to the ones shown in the table on that link. measure each pin to ground, the two pins should be pretty close to exactly the same at any given temp.

alternately, dig under the glovebox, find the ECU and ICU, unplug them, and measure from the correct pins of the plug into each module... I'll look those up later if you need them (I have a wiring diagram for your year/model that takes some digging).

 

I had a code for the ECT awhile ago and checked it out and seemed to be working, got about 2000 ohms in that 68-104* range. The code got cleared out and never came back.

Will have to check wiring to computer, I leave it plugged in and test it from the ECU>ICU side? Should get the same readings as before?

 

to test the ECT, you would unplug the ECU and ICU (vehicle shut OFF of course, I'd even disconnect the battery ground to be sure), and measure resistance (ohms) from the plug (wiring harness side) to ground. On the ECU, its pin 13 (blue/red wire), and on the ICU, its pin 2 (also a blue-red wire). again, there are two seperate thermal-resistors in the sensor, so you should check both, each to chassis ground.

 

OK I found the wires into both units. Unfortunately I'm a moron and don't know how to test them, lol. For the ECT sensor itself it was easy, ground it to the engine other one on the sensor, how on earth to do I do it in the computer part? I know dumb question.

Also, riddle me this one, lol.

For kicks I was going to test the fuel pressure. I went to relieve the pressure per Haynes: Pull fuse #4, run until it stalls and remove gas cap. So I do this and it acts the exact same way as it did before, runs for 5 min then stalled. Obviously this time because the fuse was out. I was going to check the pressure but had problem getting the line disconnected so I said screw it. Hooked everything back up. Fiddled with the control units and the ECT.

So NOW, it starts and DOESN'T stall. Which is obviously what I want BUT how on earth did it fix itself?

Tried it a couple times and each time it ran for 15-20 min before I shut it off. I can replicate the 5 min stall now.

Did running it without the fuel pump fuse knock a blockage clear or something?

 

at the computer side, you'd unplug the connector, and poke your ohm meter lead at he right pin in the wiring harness side of the plug, other lead on ground.

my guess is, unplugging and replugging everything in cleaned up a sketchy electrical connection. or yes, maybe your fuel filter is funky and running it dry jiggled the crud around enough that more fuel is getting past, I dunno. usually a mostly clogged filter will cause power loss at high throttle and RPMs, but it will idle just fine.

 

The problem was definitely fuel pump related. The in-tank pump was anemic at best and the main pump was working hard, lots of gurgling and surging and to top it off the filter was jammed up on the one side with some gunk. So working on just replacing both pumps and filter. Only hitch is the line from the pump to filter (with the banjo) snapped, oops. I hear a lot of good things about FCPEuro?

My fuel gauge is goofy too, sometimes it works sometimes its just dead and sometimes in between. could just need a cleaning when I pull the pump?