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1990 Mercedes-Benz 190E,2002 Subaru Wrx,1989 Lincoln Mark VII,1986 Lincoln Continental,Saturn Ion
Help!Engine cranks but once start
Hello All,
I'm hoping someone that has gone through my particular ordeal can help shed light on my current situation. I somewhat recently purchased this 90' 190e 2.6(though previous owner states its been swapped with the 3.0 from a 300e). Thing is the car cranks but won't catch on, I've replaced the fuel pumps, fuel filter, spark plugs, ignition coil, distributor cap/rotor and battery along with a new OVP relay. Now, I know the fuel pump relay or MAS unit is the likely culprit as I don't hear the pump priming in the "on" position however I've already went through 5 junkyard MAS units, and two "refurbished" MAS units from two separate vendors who both repaired the device in different methods. None of the MAS relays have yet to power the fuel pumps, the only time I've ever heard the pumps priming is when I jumped pins 1 and 2 with a cable but even with the pumps running the car failed to catch and start. I'm running out of ideas here, next step will be to part ways with the car and I really would like to avoid that if possible. Thanks for the time and suggestions in advance.
With relay jumped you should be getting fuel, check fuel pressure at fuel rail by checking the return line during the jump. Got return? Yes then pull fuel rail with everything attached put shot glasses under fuel injectors and cycle start with pump jumped. Got spray??? No, check for bad ground or bad ecu. Yes, check spark plus for spark. Get a tool that looks like this for checking the spark.
Got spark? Check vehicle timing then, check your air with maf or map. Generally these do not prevent no starts, but can be a culprit of super lean conditions that cause vehicle not to run.
well lets say you have all these ingredients, but still doesn't run. Answer is compression, check engine compression. Three bumps and whats the reading??? If you have good compression, your missing something that I previously mentioned.
1990 Mercedes-Benz 190E,2002 Subaru Wrx,1989 Lincoln Mark VII,1986 Lincoln Continental,Saturn Ion
Thanks for the reply, I haven't checked the fuel pressure yet. Might be worth checking out tonight. Its also been suggested that the cold start valve could be malfunctioning, could this be a culprit as well? I'm fairly certain the ignition should be set as I have replaced most everything in that category.
Just for reference, the car should start and run with the 1 and 2 pins jumped, even if the MAS control unit is removed?
1990 Mercedes-Benz 190E,2002 Subaru Wrx,1989 Lincoln Mark VII,1986 Lincoln Continental,Saturn Ion
MAS as in the MAS control unit. From what I've read, Mercedes switched over to this system around late 89 forward. I wish my car had the older stand alone fuel pump relay system, as I heard those are easier to work with. This MAS unit is supposed to control seven systems, the fuel pump relay, idle control, A/C, cold start valve and I forgot the other 3. Link below....
1990 Mercedes-Benz 190E,2002 Subaru Wrx,1989 Lincoln Mark VII,1986 Lincoln Continental,Saturn Ion
Just wanted to give an update, I got the car to fire up finally, turns out when I replaced the ignition coil I botched the install and misconnected a few wires(woops). So now the car turns on but won't idle and dies out if I'm not constantly giving it gas(a couple backfires along the way). Also, I'm still convinced that the MAS control unit is faulty as the car only starts with the 1 and 2 pins jumped. Last week I did a little experimenting with a spare MAS unit I had laying around and soldered a small gauge wire from the 1 pin terminal directly to the pole for the fuel pump relay inside the unit. Surprisingly once the unit was attached to the car the fuel pumps were priming constantly(same as if I jumped the pins 1 and 2) but when the car was cranked the engine wouldn't catch.
I ran out of time last night but tonight I'm planning on jump the 1 and 2 pins again to see if it'll catch again, IF it does, I think that throws me back to my original dilemma with the MAS unit. Can't help but wonder if the wiring harness where the MAS unit attaches to is faulty and is somehow burning out the fuel pump relay inside every time I attach it onto the car, just hard to believe that all of these units I've purchased(refurbished included) are all broken units. Update to follow soon, but if this sounds familiar to anyone please feel free to chime in.
* side note, I noticed last night that the aluminum looking module with three coil springs inside of it was heating up during the time I was cranking the car. Not sure if its something normal, I haven't found any information as to what the part is or does. Its located in the very left corner of the battery area under the hood hinge and to the left of the MAS unit.
1990 Mercedes-Benz 190E,2002 Subaru Wrx,1989 Lincoln Mark VII,1986 Lincoln Continental,Saturn Ion
Update: I recently bought a new OVP relay and got the car to fire up, car now fires up at the first crank. So pumped that the car is at this point now, but there's still an underlying issue. Car turns on but will eventually sputter out and die. Once the car stalls out, I have to pressed down on the throttle plate for a couple seconds before trying to crank it over again. Its leading me to believe that maybe there's not a constant fuel pressure being supplied and the engine is simply starving itself of fuel. I still have the fuel pump relay/MAS unit bypassed so the pumps are constantly running, not sure if that might have something to do with the fuel being cut out or if there might be an issue with the fuel filter or some other component.
1990 Mercedes-Benz 190E,2002 Subaru Wrx,1989 Lincoln Mark VII,1986 Lincoln Continental,Saturn Ion
To be honest I haven't checked the o2 sensor yet.....I'll definitely look into it. The car doesn't stay on long enough to get to warmed up operating temperature but I suppose its worth a shot.
To be honest I haven't checked the o2 sensor yet.....I'll definitely look into it. The car doesn't stay on long enough to get to warmed up operating temperature but I suppose its worth a shot.
mine would not stay on that long either. I tried a ton of other stuff and in the end the o2 fixed it.
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