1974 450SL d-jet fuel pump alternative/ car starts up and dies.. - Page 2 - PeachParts Mercedes-Benz Forum

97 SL320 · #16 11-11-2014, 04:56 PM

Quote:

Originally Posted by lovedieselsd

great info! That is these two resistors on the dr side firewall I assume? It will run for longer though, when it gets some more fuel from the cold start valve. i.e. turning the key a couple times before actually starting it. Ifound a set on a '72 350sl, I could try them. but first I'm going to have these pumps run in reverse with diesel going through. and buy me a pressure tester..

Don't run the pump backwards, there is a check valve on the outlet so you won't be able to get fuel to flow backwards.

Unless someone rewired, the cold start inj only fires while cranking and for a limited amount of time.

Install a pressure gauge and a light on the fuel pump to see what is happening. If the light goes out after the engine is running, there is a fuel pump relay or relay control issue.

lovedieselsd · #17 11-11-2014, 10:23 PM

all right, I simply put the both electric fuel pumps back, tested the 2 resistors on the firewall as far as resistance compared to the ones I found at pick a part. they were good. same with the coolant temp sensor. good too. the car still wouldn't run, as nothing really had been changed..

Took off the distributor, and opened the plate behind which the ignition points sit. a half inch spring fell out. I figured it didn't quite belong there and installed the ignition unit again. Now it runs! pretty good, good power. not very evenly, but that appears to be normal with gas motors? Never seen one run quite right, only boxer engines in VW's sometimes. V6 is the worst, who came up with that!?? Just yanking the ol' gas motor chain here heheh

anyway, all good, but when hot the idle drops down so low that battery/charging light comes on and it nearly stalls. How to up the idle some, or is this another one of those "can be this can be that" kinda things? Sensor here vacuum there etc etc?

meltedpanda · #18 11-11-2014, 10:30 PM

Is she getting enough air. Auxiliary air valve opening? Timing set?

lovedieselsd · #19 11-11-2014, 11:14 PM

Quote:

Originally Posted by meltedpanda

Is she getting enough air. Auxiliary air valve opening? Timing set?

no idea... what's the aux air valve? I mean, where? timing I guess can be better but I have no idea how to do that.

meltedpanda · #20 11-12-2014, 08:00 AM

look for the air intake into the throttle body, attached to that is a device that opens and closes based on temp, that is the AAV there should be a large screw on top that adjusts the opening and closing . Search AAV in the SL forum , or under my name you will get a lot of info on it

rowdie · #21 11-12-2014, 08:33 AM

AAV or slide valve. Located toward the front of the intake. There is a slide on the inside that gradually closes as the engine warms up. They get clogged and either don't close completely resulting in high warm idle or stick closed not allowing enough air for cold start. No screw for adjustment. The screw is the idle air screw. Use it to adjust warm idle speed.

Graham · #22 11-12-2014, 09:56 AM

Reading this thread makes me dizzy! Spring fell out of dizzy and ran better? Removed distributor and put it back but doesn't know how to set timing? Need to know where AAV is? Resistors on firewall? two pumps on djet?

A good place to start, would be to read this BW link. It covers most of the basics.

If that spring fell out of dizzy, it could be from centrifugal advance. You NEED that to be working! You can see the springs in this pic:

To adjust idle, idle screw is a good place to start:

lovedieselsd · #23 11-12-2014, 11:00 PM

Quote:

Originally Posted by Graham

Reading this thread makes me dizzy! Spring fell out of dizzy and ran better? Removed distributor and put it back but doesn't know how to set timing? Need to know where AAV is? Resistors on firewall? two pumps on djet?

A good place to start, would be to read this BW link. It covers most of the basics.

If that spring fell out of dizzy, it could be from centrifugal advance. You NEED that to be working! You can see the springs in this pic:

To adjust idle, idle screw is a good place to start:

like I said man, all I know about gas-motor powered vehicles is that they fail 10 times more often than diesels, can catch fire, use more fuel per kilometer, last less long (like the fuel in it) and smell funny. Hence I have driven and restored/ worked on diesels all my life. I've had a couple of 2CV citroens and a GSA citroen, a 911 even but after that I decided that Diesel is the way to go. Although the GSA was pretty damn fast for a 1.3. I did 185 km/h on a regular basis before they really started to control the Autoroute in France...
The truth and the life, so to speak, Diesel!! Imagine, the sheer simplicity! Which imo is what you want in a (classic) car. I have several split window busses as well, they're quite cool but they also are ever so simple as far as electrical/ vacuum/ magnetic junk to make them run.

Now, not to be a total hater, I do like this little roadster and it is a great ride. I'm sure the centrifuge-function works as I did 65 with no major issues?? I'll take off the cap and look underneath. Yes, it came with that dual pump and it works, why change it if it ain't broken I'd say? I'll read up on the d-jet, how hard can it be... I came this far. I don't think it has that idle screw though, there's a sensor at that spot instead?? not at the car now but will look tomorrow.

Thanks for the input!!

lovedieselsd · #24 11-13-2014, 08:44 PM

It seemed like a good idea to solder the 2 green wire ends together inside the distributor.... Both green, why not I thought. That condenser surely must be connected? Mind you, the car ran just fine, all I wanted to do was install the spring for the centrifugal advance or whatever it is, back. It fell inside the distributor and caused the trigger points to not trigger and caused the main issue that started the thread..

Anyway, so I installed that spring and then soldered a bit of wire to connect the 2 green end bits. Used shrink tubing to make sure there were no shorts possible. Anyway, tried starting it and heard a bit of a "pop" and after that nothing happens anymore when trying to start. one small explosion in the exhaust, that was it.. I guess I fried the computer or so. I undid the soldering so now the condensator is not attached anymore. Everything is like it was before (when it ran) only the spring has been put back in place. But the car is dead. nothing at all. I'm so bummed out, I have 3 full weeks of work in it and I'm about to give up. Any input highly appreciated before I start calling around to donate it. Tried another coil, thinking that got shorted, and checked ceramic resistors on firewall. fuel relay is good, the pump turns for a second when turning the key.
I'm at the end of my energy to get this car on the road.

lovedieselsd · #25 11-13-2014, 08:48 PM

3rd pic is of a "thing" that just hangs out there. It looks like one of the spark plug wires is supposed to go through it? What's that for??

lovedieselsd · #26 11-13-2014, 09:30 PM

was this car running without the condenser hooked up and a dual fuel pump putting out too much pressure, sending huge sparks to the bougies and is that why it ran?? And now somehow the points got fried? And how is there only 1 wire going (well there wasn't at all

) to the condenser??

I bet somebody who had the car before me "adjusted" the spark to work with the dual fuel pump... How many pounds should that d-jet pump put out anyway, 39psi?

Graham · #27 11-13-2014, 10:31 PM

You dont need a condenser if the ignition is original. Just remove it. The wire from the points needs to be connected to a green wire that runs from distr to a connector down below coil near resistors. It must not ground out anywhere so insulate it where it passes out of distr. Set points at 0.014".

Your fuel pressure should be about 30 psig.

lovedieselsd · #28 11-14-2014, 11:24 AM

Quote:

Originally Posted by Graham

You dont need a condenser if the ignition is original. Just remove it. The wire from the points needs to be connected to a green wire that runs from distr to a connector down below coil near resistors. It must not ground out anywhere so insulate it where it passes out of distr. Set points at 0.014".

Your fuel pressure should be about 30 psig.

But why did it completely fail after hooking up green wire to resistor... Did that fry my points? Or is it the new spring for the centrifugal advance? can anything else have gone bad installing that wire to the condenser?

LUVMBDiesels · #29 11-14-2014, 11:28 AM

Is the pump running once the engine starts?
Did you check the fuel pump relay? try jumping it and see if the pumps keep running. The fuel pump relay is located above the fuse panel.

You want to jump pins 87 and 30 as a test.

You can also run a line directly from the battery to the positive terminal on the pump to make it run as a test. You do not want to leave that set up.

Graham · #30 11-14-2014, 12:32 PM

Quote:

Originally Posted by lovedieselsd

But why did it completely fail after hooking up green wire to resistor... Did that fry my points? Or is it the new spring for the centrifugal advance? can anything else have gone bad installing that wire to the condenser?

I don't know just what you connected to what, but that green wire from points does not go to a resistor. It goes to switchgear and tach, sometimes via a terminal near resistors, but that depends on model year. A 74 is different from my 72, but the manual should have a wiring diagram.