1984 380SEL no fuel questions - Page 2 - PeachParts Mercedes-Benz Forum

Mike D · #16 05-28-2009, 12:55 AM

All right. So, tomorrow, you undo the fuel supply line and do the flow test. The fuel pump electrical connections are still original, correct? The large post is ground and the smaller one is positive. The pump will run backwards.

It goes like this, fuel feed from the tank to the inlet of the pump, compression through the fuel filter, out through the accumulator and up to the fuel distributor on the intake manifold. The accumulator "back feeds" the pump and holds pressure (1 bar) while the car is not running. It also serves as a baffle to smooth the fuel flow.

Fuel pressure is fed to the distributor, is regulated by the primary regulator, goes into the upper chamber, forces down the piston, feeds into the warm up regulator which regulates the system pressure, feeds back into the distributor by the primary regulator, either passes out through the injector lines or is fed back into the return line. There is also a "supply" side of the system but you aren't ready to worry about it yet.

Either the junkyard pump is just that or you might have the wires reversed. Stranger things have happened.

So far on my project; I've pulled and cleaned the injectors and lines (twice!), changed plugs 4 or 5 times (I keep fouling them), pulled and cleaned the distributor, replaced the injector seals and air tubes, ran a separate tank to eliminate the nasty old fuel tank, flushed the system by running cleaner through it for an hour or longer, just tonight I pulled the WUR , dis-assembled it, cleaned it and tomorrow I will be putting it back on for another go at starting it. If that doesn't work then my next step is to yank the pressure regulator and clean it. If that doesn't work then I'm saying to heck with it and Megasquirting the mutha!

No way I'm spending $700+ for a rebuilt distributor!

I feel for ya! I'm going through this also. The last time I dealt with the CIS system was about 20 years ago and that was on an abused old Audi 100LS. It's a great system unless it's been neglected. Sigh...

Douge · #17 05-28-2009, 01:12 AM

On the fuel pump, the posts are different sizes and you cannot wire it incorrectly.

I will report back tomorrow.

I will buy you lunch/dinner next time you are around or I run down to Tuscon. We can either celebrate or commiserate depending on the circumstances.

Douge · #18 05-28-2009, 11:18 AM

I am going to try routing a fuel line directly off the fuel filter to the engine but still not sure where the primary inlet into the injection system is????

Any help?

Douge · #19 05-28-2009, 12:04 PM

OK, the fuel pump from the yard was bad. I think they have another or I will try a third source today.

I disconnected the fuel line and ran a purge line to a gas can and jumped the fuel pump relay. Before I jumped it I measured 12V at the relay. Got nothing. So I need a good fuel pump.

I checked all the readings on my 420SEL and that pump is getting 13.3v at the pump and making noise. The other pump was getting 9v, making no noise and not moving fuel.

Not sure if I have a voltage prob to the fuel pump, but 9v seems low in relation to the 13.3v on the 420sel???????????????

Mike D · #20 05-28-2009, 01:54 PM

9 volts is low but if I remember right you were checking the voltage while cranking the starter. A lot different than just jumpering the relay.

Douge · #21 05-28-2009, 01:59 PM

Quote:

Originally Posted by Mike D

9 volts is low but if I remember right you were checking the voltage while cranking the starter. A lot different than just jumpering the relay.

True story. The engine was running and generating current when I measured the 420SEL.

I am thinking as much of a hassle as its going to be, I might take the pump off the 420 and trying it on the 380 just to see if that is in fact the prob.

Mike D · #22 05-28-2009, 11:16 PM

I give up! Mine beat me. I cleaned and re-installed the WUR, initial pressure dropped to 25 PSI, but the piston in the distributor stuck shut. System pressure was right at 70 psi with the check valve closed but the distributor gave up the ghost. I'm Megasquirting this beast!

Do you want all the CIS stuff I'm removing? Injectors with new seals (cleaned and marginal), new air tubes, new injector sockets with O-rings (one is bad, I nicked it removing the receptacles), cleaned and operable WUR, injector fuel lines, WUR feed and return lines, POS fuel distributor and all the other valves, relays and B.S. which goes to the CIS?

PM me with your address and I'll box the crap up and send it to you.

Douge · #23 05-29-2009, 12:06 AM

Oh oh.....

Douge · #24 05-29-2009, 01:35 AM

It was ALIVE briefly. Fuel pump is now working. It started and ran for about minute and then died and would not restart and stay running. I could smell the bad gas and wished I had thought to purge the lines first!!!!

Gonna throw in some fresh plugs tomorrow, but I am with you, about to pull the plug or at least keep jr. from dropping anymore coin on this one.

You have mail.

Douge · #25 05-29-2009, 08:48 PM

Wow, I think I am going through what you are dealing with. It started right up after new plugs and fuel line purge and we went to take it around the block and it quit after 50 yards.

Arrggggghhh

Douge · #26 05-29-2009, 11:29 PM

OK, I actually got to drive it. I got it started again and let it idle for several minutes and then gradually applied throttle and it kept running. I wound up driving it for about ten miles!!!! Runs pretty strong, trans seems to be good.

Brakes, drivers front, metal on metal. Power steering is leaking, both valve cover gaskets leaking. But at least we got something to work with!

Mike D · #27 05-30-2009, 06:34 AM

All right! Good job. What did you do to get it running? Be careful, you'll get your son hooked on restoring old cars!

Douge · #28 05-30-2009, 05:18 PM

Hey, I called you back, right after I got off the phone I went out to roll up the windows and I decided to try it again and after it started I thought, hey just let some of the treated gas start working through it and sure enough it kept running.

Fired right back up this morning and we just finished doing the brakes, Christian did one side solo! That was cool to see him complete something on his own. He is out washing it and I will post a pic.

Douge · #29 05-30-2009, 06:49 PM

Mike D · #30 05-30-2009, 08:15 PM

SSSuuuuWWWeeeeTTTT! You know of course, this will mean a life long addiction for your son?

Sigh, it won't be long, pretty soon he'll spot that lonely SL,"But Dad, I KNOW it won't take that much to bring it back to life!".

He'll be dipping into sheet metal welding, late night tuning binges, having a second job to pay for those leather upholstery repairs,...

Just think of what you are doing, teaching your son to be self-sufficient!

Ain't it great when stuff works out!

The stuff is in a box and I'll be sending it Monday.