C280 Fuel Problem - when parking on an angle

[SL600-Cruzin]

A friend has a 96 C280.
The problem is, whenever the car is parked with the front-end lower than the rear-end the car won't start. Acts like it's getting no fuel.
When indeed there is 1/2 tank .

Since I don't have the car here to test fuel pressure etc.. My Question is, could it be that the Fuel Pump is getting tired and can not suck against the angle of the vehicle ? or could have the pickup tube in the tank got jacked up somehow ?

I can't imagine this being the case, but is it just common knowledge not to park these cars on a grade with the front-end down?

Any help is greatly appreciated!

Thanks
TJ

[bwheitman]

That is really strange. I would test the fuel pressure at that angle, I would guess you can hear the pump going? Is it sucking air? don't forget there is a bowl in the tank to prevent the fuel pump from sucking air while in curves or angles, maybe that is defective. Overall a pressure test while at an angle that creates the problem will tell you a lot. Has the fuel filter been replaced regularly? That can weaken a pump, maybe it is just on it's way out.
Good luck!
Brian

[SL600-Cruzin]

Originally Posted by bwheitman

That is really strange. I would test the fuel pressure at that angle, I would guess you can hear the pump going? Is it sucking air? don't forget there is a bowl in the tank to prevent the fuel pump from sucking air while in curves or angles, maybe that is defective. Overall a pressure test while at an angle that creates the problem will tell you a lot. Has the fuel filter been replaced regularly? That can weaken a pump, maybe it is just on it's way out.
Good luck!
Brian

Thanks for the quick response, to answer your questions... it is indeed strange, I can't check the pressure right this min as the car is located about 60miles from where I'm at so this is diagnosis on the fly. (really hoping someone had experienced this before and had a quick easy fix). The pump does run, and you can move the car to where it's not at an angle and then it will start up and run like usual.

Also, I realize these cars had issues with getting the correct fuel filter for them, so with that said, I replaced the fuel filter a while back and it made no difference. Did the same thing before and after new fuel filter.

Could you please explain what you mean by "bowl in the tank"? Is it the expansion reservoir you are talking about ? Or are you talking about the pickup tube ?

The car runs absolutely fine all of the time, no problems with acceleration and drives like a dream. It's just when it's parked on a slight downward grade (front-end facing down) and has sat for a while (4-6hrs). The symptoms are that of a pump that lost it's prime for some reason.

Also, does anyone know exactly what the Fuel pump check valve does for the system in question ? Does it maintain system pressure while the car is off, ie.. keeps the pump primed ?

The fuel pumps are pretty pricey for these things, so I want to figure out what it is before I tell him to start throwing parts at it. LOL

I sold him the car so I feel obligated to help him fix it. Thanks for your continued help
TJ

[bwheitman]

The bowl in the tank is called a splash bowl, take a look here and it will explain it's function. http://www.mbca.org/northtexas/fuel_system.htm

Hmmm, maybe I would remove the access to the tank and inspect it. I have never heard of any of the lines coming loose or getting bent, but if the pump is sucking air then that is the only thing it could be, the line either came loose from the splash bowl, or it is clogged. I am not entirely familiar with that model, but the more I think about it it sounds like a fuel pump. Where is the pump located? I would park it on an incline, at failure (not starting) remove the pump from the chassis and decrease the angle of the pump and see if it starts to pull fuel. If that is the case, it is something wrong with the pump, if it doesn't pull fuel, but is running, then you may have a tank issue and that will involve removing the access panel and inspecting the inside of the tank, it is unlikely anything has come loose in there, but it is possible. Good luck.
Brian

[bwheitman]

Just a thought, could the filter be in backwards?

[SL600-Cruzin]

Thanks for the continued help.

The filter is in correct AND it is even the correct one

The car runs perfect 99% of the time. It's just once in while, when it's parked on a downhill grade and sits for over an hour, it doesn't want to start. You can get out and push it onto level ground or get the front-end higher than the rear-end then it starts up and runs fine again until it gets into a similiar position. Then sometimes you can park on a downhill grade and there's no problem. That's what leads me to believe it could be the fuel pressure check valve. Or as you mentioned, maybe a weak fuel pump. But one would think that a weak fuel pump would show other symptoms, such as starving at high speeds etc..

I'll see if I can't get my hands on the car to do some pressure testing etc..

Was just hoping that someone here had the same problem before and had a quick fix for it.

Anyway, thank you !!

Have a good one !
TJ

[SL600-Cruzin]

Problem Fixed !

When the car wouldn't start the last time, I ended up pulling out the fuel pump relay and tapping it on it's side on the ground. Reinstalled it and wha la it fired up.

Replaced the Fuel Pump Relay and all has been good since.