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GeraldK

Canada
89 Posts

Posted - 07/25/2017 :  23:57:42  Show Profile  Reply with Quote
I adjusted the pump mixture with the 10 clicks and there was no noticeable change and turned it back the clicks.

Having a closer read through the shop manual I came across the section for setting the linkages between the throttle body and the injection pump. With the links disconnected both levers sit against their stops. However when connecting them back up, the lever at the pump is no longer against the stop. It's moved up to the 3 mark. The link connecting to the throttle body is also very bent. I believe I have previously tried to run the car with this disconnected and still have the idle problem. I will have to double check tomorrow. Maybe I should also try the pump adjustment with the link disconnected and see if helps.

I also read that I shoulld disconnect the supplementary air line to the air filter and check at what temperature here is no more suction.

I hooked up a vacuum gauge between the intake manifolds where a small vacuum line comes off. I assume this is for the door locks? I measured 15 Hg at this connection which seems to be the low limit of good vacuum. It held steady at this reading. The manual references a test connection at the throttle body. This is the line connecting to the vacuum advance on the distributor? I could not get a reading there.





Gerald
1969 300 SEL 6.3 #0795
1959 190 SL
Calgary, AB

Edited by - GeraldK on 08/06/2017 20:55:30
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mpmorris

USA
1302 Posts

Posted - 07/26/2017 :  11:25:41  Show Profile  Visit mpmorris's Homepage  Reply with Quote
Mystery --I'd have the injection pump and throttle housing linkage disconnected during this warm-up/idle test -again I'd set throttle stop to 1/2 turn from full idle stop (butterfly binding). I'd have a basic idle timing adjustment at TDC. The air piston for the choke is working according to your post (idle drops during warm-up).

As the engine gets close to warm-up but before the idle goes away, lift the throttle butterfly --if the engine will not raise rpm it is too lean. If the rpm rises it is just right -if it rises a lot (more than say above 1500), it is too rich. You simply may have to turn the pump in more than 10 clicks which would indicate your injection pump is out of time.

mpm
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GeraldK

Canada
89 Posts

Posted - 07/26/2017 :  12:42:10  Show Profile  Reply with Quote
I'll keep working through it based on your comments. Should I double check fuel pressure just to eliminate it being a possible issue? This is done at one of the fuel lines going to the CSV? I'm just trying to figure out what kind of tester/fitting I need.

One of the last tests I did last night was with the pump set back to its original setting and the butterfly link disconnected was to open the butterfly manually, the engine dies instantly. However this was done when it was already running rough.

If it turns out to be the pump out of time I'll be disappointed with myself! I did take note of the proper timing marks when re-installing.

Gerald
1969 300 SEL 6.3 #0795
1959 190 SL
Calgary, AB
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mpmorris

USA
1302 Posts

Posted - 07/26/2017 :  14:58:21  Show Profile  Visit mpmorris's Homepage  Reply with Quote

"open the butterfly manually, the engine dies instantly"

--lean condition. Ten clicks should have been sufficient as a test. --very hard to believe the injection pump came back this far out of whack.

Given that 'A', your fuel pressure is possibly too low; or 'B', your injection pump is out of time; I'd do a flow and pressure test at the engine side of the fuel filter. Get the basics first. --low fuel pressure definitely will cause your symptoms.
.
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GeraldK

Canada
89 Posts

Posted - 07/26/2017 :  16:34:19  Show Profile  Reply with Quote
I just have a typical vacuum/pressure tester. Is this all that's needed? I would just need a piece of hose with the proper fitting to attach to the fuel line going to the CSV? What thread would be required?

Gerald
1969 300 SEL 6.3 #0795
1959 190 SL
Calgary, AB
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mpmorris

USA
1302 Posts

Posted - 07/26/2017 :  22:09:04  Show Profile  Visit mpmorris's Homepage  Reply with Quote
.
Hmm. --This is a dicey area -you could have a lot of fuel spraying --followed by a call to the fire rescue squad. --I'd find a competent person with a correct set of fuel pressure gauges to assist you.

mpm
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GeraldK

Canada
89 Posts

Posted - 07/26/2017 :  22:41:42  Show Profile  Reply with Quote
I would just pick up a proper tester or see if any of the local shops rents them out. According to the shop manual all the pressure tests are done without the engine running.

Would pinching the return line after the rear damper be a quick test to see if its pressure related?

Gerald
1969 300 SEL 6.3 #0795
1959 190 SL
Calgary, AB
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daantjie

Canada
909 Posts

Posted - 07/27/2017 :  13:59:18  Show Profile  Reply with Quote
quote:
Originally posted by mpmorris

.
Hmm. --This is a dicey area -you could have a lot of fuel spraying --followed by a call to the fire rescue squad. --I'd find a competent person with a correct set of fuel pressure gauges to assist you.

mpm



Gerald is from Calgary, these cowboys like to do things differently up there

Daniel
1977 450 SEL 6.9
Vancouver, BC
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GeraldK

Canada
89 Posts

Posted - 07/27/2017 :  15:32:03  Show Profile  Reply with Quote
quote:
Originally posted by daantjie

Gerald is from Calgary, these cowboys like to do things differently up there

Daniel
1977 450 SEL 6.9
Vancouver, BC



Maybe I should put some fire insurance on the car before doing any testing! We're not all cowboys here in Calgary. I don't even put on cowboy boots during Stampede.

Had a closer look at the tester I have and it only goes up to 10 psi so that won't work. Will either have to buy a proper tester or see if one of the local shops lends them out.

Gerald
1969 300 SEL 6.3 #0795
1959 190 SL
Calgary, AB
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GeraldK

Canada
89 Posts

Posted - 07/28/2017 :  09:55:01  Show Profile  Reply with Quote
I'm wondering if its possible the fuel tank that I sealed is not delivering enough fuel. I did not perform the return flow test according to the shop manual. I checked the fuel volume at the hose feeding back in to the tank. Only about 300 mL was delivered. Tank definitely isn't half full as is recommended for this test.

Also disconnected the fuel outlet hose at the fuel pump and the same amount of fuel was delivered. I would have expected a lot more fuel to be delivered with this test.

Not sure if these tests are valid. Not sure how much fuel is left in the tank as I don't have the the fuel sender hooked up, just capped off the opening. I only started with ~20 L in the tank.

Gerald
1969 300 SEL 6.3 #0795
1959 190 SL
Calgary, AB
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Art Love

Australia
6152 Posts

Posted - 07/28/2017 :  19:48:03  Show Profile  Reply with Quote
It would be great if it turned out that you were just "out of gas"!
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GeraldK

Canada
89 Posts

Posted - 07/28/2017 :  20:20:09  Show Profile  Reply with Quote
Haha, that happened to my father many years ago. It was on one of our very cold winter days and he spent hours out in the cold trouble shooting the issue. Even went as far as heating up the spark plugs in the oven. Turns out someone had siphoned the fuel from the tank.

Gerald
1969 300 SEL 6.3 #0795
1959 190 SL
Calgary, AB
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AgSilver

USA
217 Posts

Posted - 07/29/2017 :  10:47:54  Show Profile  Visit AgSilver's Homepage  Reply with Quote
You must have adequate flow in addition to pressure. You can have the proper pressure of about 12 PSI with restrictions in the plumbing. Be sure that the fuel filter and the fuel tank screen are both clear. I experienced similar symptoms early in the restoration process during the initial startup of the rebuilt engine (https://www.youtube.com/watch?v=jzX9H9DoqVc). The engine ran perfectly (the lope is from the re-profiled camshafts) but as the MFI pump gradually heated up the engine would eventually stall. Replaced the worn out Bosch pump with a modern positive displacement gear rotor pump - - - problem solved. About 3 years ago I was stuck in New York City traffic for about an hour on a 103F degree July afternoon. No vapor locking whatsoever and no problem restarting the heat soaked engine. Only thing missing was a modern A/C system as the original Behr on 134 was really struggling.

Palm Beach Gardens, FL
Niederheimbach, Germany
300SEL 6.3
E55K AMG
CLK63 AMG Gone
Ferrari 400GTC4 Gone
ML400CDI BiTurbo
ML350 CDI BT
9146GT
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GeraldK

Canada
89 Posts

Posted - 08/28/2017 :  20:27:05  Show Profile  Reply with Quote
I'm hoping that I may have finally got to the bottom of the fuel delivery problem. I ended up swapping out the fuel tank as the old one was barely flowing any fuel after I tried to seal it. Unfortunately my idle issue persisted.

I recalled Michael mention that an incorrect fuel filter (diesel filter) will cause my symptoms. I had installed a filter my father purchased for the car from the dealer 16 years ago. I had a copy of dealer invoice with the part number on it and checked with Tom if it was the correct part. Turns out it is in fact a diesel filter. I should have the correct filter from a local parts store tomorrow. If I have time I will try and instal it tomorrow and see if this has finally been solved.





Gerald
1969 300 SEL 6.3 #0795
1959 190 SL
Calgary, AB
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Ron B

Australia
11554 Posts

Posted - 08/29/2017 :  20:22:38  Show Profile  Visit Ron B's Homepage  Reply with Quote
I posted a few pictures on cleaning and resealing the fuel tanks for our cars a couple of months ago. If you use POR15 tank sealer you have to blow through the inlet and outlet pipes while the stuff is sloshing in the tank to make sure the ports remain open. I also jamb masking tape or paper into the venturi on the swirl pot in the tank which I fish out afterwards to make sure that stays clear too. Once set,that stuff is pretty well impossible to remove. When doing any tune up work you must always start with the ignition and then start with fuel flow and fuel pressure tests. Actually touching the MFi is the last thing you do.
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