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W124
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Robert,
The attached is related to what I call the fuel pump
IMG_6310.JPG
"barrel connector". The image shows the connector on my '94 M104 so its different from yours. Yours should be upright, and wire tied to the bulkhead. This shot was taken while looking down at the positive terminal side of the battery. When connectors aren't tied to the bulkhead, they can easily be pushed apart when the OVP/ECU/ABS area plastic shield is being installed. As the shield is being pushed down, it grabs the connector and the two halves come apart. IIRC, there is no locking feature on the connector so both halves being tied to the bulkhead is all that keeps them together. Its worth checking this before you start digging deeper.
 

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1994 e320 coupe (sold), 1990 300CE ($400 beater)
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Discussion Starter #22
Still can't find any such barrel connector on my 1990.

BTW...is there a rollover switch that gets triggered when the car rolls over, it shuts off the fuel pump(s)? My old Jag had this.

20200317_081649.jpg 20200317_081655.jpg 20200317_081658.jpg 20200317_081703.jpg 20200317_081708.jpg
 

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Humor me here. You say you have spark and the engine cranks. You also can make the fuel pumps run with a jumper at the relay. What happens when you spray starting fluid directly into the large round air flow flap of the air flow assembly?
 

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1994 e320 coupe (sold), 1990 300CE ($400 beater)
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Discussion Starter #24
Nothing. No help when spraying starting fluid in the TB.

Spark plugs are pretty dry, so definitely not getting fuel. Unless I put a jumper, but even then, they're barely (barely!) damp.
 

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Robert,

If you have starting fluid flowing into the intake manifold, then it replaces the need for fuel for ten seconds or so. This is why I asked for this test. It sounds like your spark is not getting to the plugs. How did you test for spark? ( is the distributor rotor still on the bench?) :)
 

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1994 e320 coupe (sold), 1990 300CE ($400 beater)
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Discussion Starter #26
I removed the coil wire from the dizzy cap and stuck a screw driver. Definitely lit up.

Worst case scenario is that I jumped a tooth when i removed the timing cover and tensioner? I highly doubt that tho.
 

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The only test of spark that's valid is to pull a plug and ground it with the HT lead on it. Crank the motor and observe spark across the gap. This should be a healthy blue spark. Do this with all plugs. Do a compression test. If you had "jumped a tooth" the car will still start. If you have spark in all six cylinders and compression in all cylinders, after spray starting fluid directly into the air flow meter (round disk) the car will monentarily start.
 

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1990 Benz 300E 2.6 (mine) ; 1994 E320 Wagon (wife's) ; 1993 300CE Cabrio, needs some TLC
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BTW...is there a rollover switch that gets triggered when the car rolls over, it shuts off the fuel pump(s)? My old Jag had this.
when the engine stops turning, the fuel pump stops. there's probably a rollover valve in the fuel tank ventilation.
 

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1994 e320 coupe (sold), 1990 300CE ($400 beater)
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Discussion Starter #29
Actually found the barrel connector. It's actually on mine, in FRONT of the battery. Seems tight as heck with wire ties holding it in.

When...new OVP, different MAS...no difference.

Got plenty of spark from one of the spark plugs.

Sprayed plenty of starting fluid down the tower.

Nothing.

The ONLY thing I can think of that I may have messed up is that it was pretty cruddy in there, so I sprayed some engine degreaser and water around the water pump area. Nothing else really. Nothing near the intake maniflold/etc.
 

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1994 e320 coupe (sold), 1990 300CE ($400 beater)
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Discussion Starter #30
Popped a fuel line that goes to one of the injectors. Barely a dribble of gas.

So...thinking more and more the fuel pumps? It's possible there's voltage going to them; I don't have a helper (hopefully soon) to check voltage while cranking.
 

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Good progress, tracking down the spark. Okay so now you need to figure out how to jumper the fuel pump at the relay so you can confirm it is capable of running and providing fuel to start and run the vehicle.

Try this:

If you can get the engine to start and run this way, then you will have proven one important thing - that the harness from the relay to the pumps is sound and the pumps run. But one step at a time. Do the jumper test. Could just be a bad relay.
 

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1994 e320 coupe (sold), 1990 300CE ($400 beater)
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Discussion Starter #32
well...had a helper crank the engine while putting meter on the fuel pumps. Odd that seems like they seem to be getting 10v???
 

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89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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Considering they take 10A each, a 4V drop (0.2 -0.4 ohms along the way) is not that significant.
Do both get the same voltage?
 

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89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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So assuming they are consuming the expected 10A each, that is only 0.1-0.2 ohm from your battery. Not too unexpected.
 

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Good diagnostic work. Okay so the voltage is at the pumps and I presume you have ground? Do the pumps run when you turn the key to the on position (on - not start)? Next diagnostic is fuel pressure reading at the fuel distributor. Let us know what you find. If you want to jump ahead and kill two birds at the same time, do a compression test too. If you have compression and fuel pressure but still no fuel spraying at the injectors, then the control piston in the FD is stuck or its travel is very limited. (or there is an obstruction in the fuel line.)
 
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