No Fuel - PeachParts Mercedes-Benz Forum

Billro · #1 02-07-2006, 01:26 PM

I have a 1985 190E, fuel injected. It stalled while driving along about 25 mph. restarted after a short wait and went about a mile before stalling again. I have excellent fuel flow to the fuel distributor inlet but can't getany past that point. I did hold down the air plate while trying to get flow through the distributor. What could shut off the fuel here?

300EVIL · #2 02-07-2006, 08:15 PM

Bump

dave_rose69 · #3 02-07-2006, 11:01 PM

Did you hook up a fuel presure gauge to the inlet side with a T fitting? Youre looking for about 80psi. Its possible the fuel pressure regulator is not restricting and theres no pressure to charge the fuel distributor. Volume delivery is important, but the pump or pumps, must pressure up too. Get the gauge going, and if your direct pump pressure is 90 to 100 psi or more, and then with the T in between the main fuel feed and fuel dist, your pressure is way low, you need a FPR. Dont test the FPR by clamping the return line, it will crack that old line and or possibly damage the fuel dist by over pressuring it.
Dave....
How did you know you werent getting fuel injection from the distributor?

Billro · #4 02-08-2006, 07:55 PM

Dave-Thanks for your reply. I felt that I had no fuel coming out of the distributor because I alternately cracked some of the lines exiting and got no signs of fuel. I also cracked the one to the pressure regulator and again got no fuel. This was all done with the air inlet valve pushed down.

mctwin2kman · #5 02-09-2006, 08:57 AM

Can you hear the pump running?

First check your fuel pump relay. Then verify fuel pump is running. You can jumper the realy socket to force pump to run. Then if the pump works and no fuel flow then replace the fuel filter. Cheap part and most likely needs it if it has not been done in the past. With a stall at speed I would assume that the filter is clogged, pump is dead or pump relay is dead.

sbourg · #6 02-09-2006, 09:14 AM

Pump pressure, to re-iterate. Flow rate doesn't mean much if the pressure isn't there.

Steve

mctwin2kman · #7 02-09-2006, 12:11 PM

Quote:

Originally Posted by sbourg

Pump pressure, to re-iterate. Flow rate doesn't mean much if the pressure isn't there.

Steve

If the filter is clogged then you will get no pressure obviously.....

Billro · #8 02-09-2006, 01:34 PM

OK. The fuel pressure is 30 PSI. The pump and filter are less than 1 year old. I will try anew filter. Sure am glad I cracked those injector lines.

kaskae · #9 02-09-2006, 06:03 PM

i had a a almost identical problom on my 85 5.0 ,,,it would stall and then after 15 20 min it would start. Iit turned out to be a leaking vacuum line to the pressure regulator valve on the back side of the fuel distributer, this also affected my heating system by shutting the inlet off when i stepped on the fuel, it was very puzzling for a day,,,,hope this helps

sbourg · #10 02-09-2006, 08:15 PM

Quote:

Originally Posted by Billro

OK. The fuel pressure is 30 PSI. The pump and filter are less than 1 year old. I will try anew filter. Sure am glad I cracked those injector lines.

Ok, a clogged filter will restrict flow, but NOT static pressure! Pressure that low means likely a bad fuel pressure regulator, or possibly a bad pump.

Steve

dave_rose69 · #11 02-11-2006, 11:39 PM

If you are testing the pressure at the fuel distributor inlet, (rhs of unit), and its low, do a direct pump pressure test at that same delivery line, except dont use a T fitting, just connect deliv line straight to gauge. You need around 85 to 100 psi or more. If you still have 30 psi, there are a few things that could cause that. 1. fuel accumulater isnt holding pressure (you can plug its return line to see if pressure comes back up) 2. pickup screen in tank is dirty. 3. fuel filter clogged. 4. bad pumps 5. insuffcient voltage to pumps (bad relay contact) this would be rare, its either there or not. Do a fuel pump voltage test. 13.5vdc+ First get your straight pump pressure fixed, then worry about the FPR. Your goal is to have 80psi with the T fitting between the deliv line and fuel distributor.
Dave...

Billro · #12 02-15-2006, 07:35 PM

My direct pressure is 30psi. I plugged the return on the accumlator and got 30psi again. I changed the fuel filter as long as I was in the vicinity and briefly removed the line from the tank. The flow from that line was impressive so I think the tank screen is clean. I have ordered a new pump as my next step. By the way, Arizona ******** is having a great sale on Bosch component through February. So right now Iam just waiting for the UPS girl.

dave_rose69 · #13 02-15-2006, 11:26 PM

Its a possibility your pump stator vanes are worn down so much, they are not able to pump enough to attain operating pressure, but generally, a bosch pump will fail from worn motor commutator brushes or bearings first. After all the tests you have performed, it certainly sounds like the pump is weak.

sbourg · #14 02-16-2006, 09:15 AM

Check flow from fuel return line at the FPR. If you have flow, the FPR is bad. At 30 psi, there should be none.

Steve

dave_rose69 · #15 02-16-2006, 06:40 PM

A direct fuel pump pressure test, is hooking the fuel pressure test gauge directly to the delivery side of your fuel hose. Do not use a "T" fitting between the main line and fuel distributor-FPR. (Just to clarify)