NordicSaab

Hey Rennlist. I hate to post another car will not start thread but I am at my wits end and I need some direction. I have divided what I know about the car into the 3 categories necessary for the car to start air, fuel, electrical, spark. I am happy to do whatever diagnostic tests recommended in order to narrow down the problem(s). Thank you in advance for the help.

Car
-1981 Euro S M28/11
-CIS Fuel Injection System
-Manual Transmission
-Car ran when purchased (not well)

Car ran when purchased, but a small engine fire led to a wiring harness rebuild. New harness has been installed. After the fire I took off the whole intake system to clean the motor. This included a thorough degreasing of the CIS "diaphragm" and throttle body. Much rubber was replaced at this time as well. Both fuel lines from the supply line to the Fuel distributer were replaced as well.

At this time the car will crank, but shows very subtle initiative to start.

Electrical
-New Fuel relay
-New Engine Harness

Until recently the fuel pump would kick on with the turn of the ignition. Now the fuel pump does not kick on with the relay or with a relay jumper in place. With a multimeter I have tested and found that 12V is going across the relay from pin 30 - 87. I can also hear the relay click when It is in place and I turn the ignition. It would seem the relay is good, but the line to the fuel pump is pulling 12V without starting the fuel pump.

At the fuel pump I have run battery directly to the + side of the pump and the pump does engage. It does this without any additional ground. This would lead me to believe I have a good ground. For further understanding I ran a jumper direct from pin 30 on the fuel relay port to the + side of the fuel pump; The pump did not engage.

At this time I have not dropped the tank.

Fuel
-New Fuel Accumulator
-New Fuel Lines
-New Fuel Injectors (Mercedes)

I have cracked each injector line and confirmed I have pressure at the injector. I also pulled the line off of injector #1 and put a spare injector on with the fuel pump hard wired to the battery. Without depressing the CIS AFM door no fuel would come out of the injector. Once I manually depressed the CIS AFM door the injector would trickle fuel rather than producing a spray pattern. The CIS AFM door also seems very heavy to actuate. At rest the CIS AFM door is closed almost completely shut.

Spark
-New Spark Plugs
-New Rotor Cap and Dizzy

I have tested with an injector light and I have spark at the injectors.

Air
-New Vacuum Lines
-New Throttle Socket Gasket
-New Intake Couplers

As stated earlier, The CIS AFM door seems very heavy to operate. I would estimate force to be a couple of pounds to manually depress. Car currently does not have air box installed.

I have provided everything I know to the best of my ability. I don't know where to go from here. If there is a test I should be running please let me know and I am happy to conduct it. Thank you again

LT Texan

Fuel pump runs with a wire directly from the battery, but not when the relay is jumped? And you have 12v at the relay.

Does the wire from the relay to the fuel pump have continuity?

NordicSaab

Ran continuity from the 87 pin to the + side of the furl pump and I have a "0" reading. So, yes, I have continuity.

GlenL

Often a problem with CIS is the opposite: it starts running but dies. It starts because the Cold Start Injector is spraying. Since yours doesn't start and you replaced the wiring I'll guess that there's no power to that injector when cranking.

NordicSaab

Cold Start Injector was removed when I redid the wiring harness. The fuel port at the fuel distributor was plugged and the line forward removed.

jpitman2

You are not going anywhere until you get systematic with the fuel system - pressure gauge set needed asap! Follow the manual and test - return flow (1360cc/30 secs), system pressure (65-75psi, 4.5-5bar), cold control according to the chart in WSM (< 20 psi). A hard air plate can be a sign of high control pressure. I dont know how cold it gets in FL, but the cold start injector was fitted for a reason....
jp 83 Euro S AT 55k

michael j wright

On my 82 euro, the fuel pump does notrun untill i start to crank. Have you tried to run a wire from the 12v side of the relay to the pump? also have you replaced the fuse? I had a fuse to the fuel pump "look" good, but when replaced resolved my problem.
Good luck, and let us know.
Mike
]

LT Texan

Jumping the relay doesn't make the fuel pump run.

I'd move no farther until that is sorted out.

jpitman2

My pump also does NOT run with ign on, only while cranking. I burned out 2 pump relays before I found the pump fuse was makjing poor contact - I actually saw a spark come off the contacts while I was working on the issue.
jp 83 Euro S AT 55k

LT Texan

Yep, if you can't get the pump to run by jumping it at the relay, nothing else you do will make the engine run.

GregBBRD

If you have 12 volts, through the electrical system and the pump doesn't run, but it runs when you hook up a separate power wire to the pump.....well, that's highly unlikely.....unless the pump just needs a little bit more voltage/current, in order to run. If so, you need a pump.

Are you checking the voltage to the pump under load (hooked up to the pump?) Always check all voltage readings under load....common mistake to not do this. A bad connection may allow 12 volts at 1/2 amp to flow, but might drop away to virtually no volts when you ask for a 10 amp draw.

NordicSaab

Thank you everyone for the feedback.

I have ordered a CIS testing kit as well as a new fuel pump.

Today while waiting for feedback I drained the fuel tank, removed the fuel pump, and removed the fuel filter. Over the next couple of days while waiting for the new fuel pump I will more thoroughly investigate the electical to the fuel pump. I will also replace the fuel pump fuse to ensure it's integrity.

jpitman2

And replace the filter unless YOU KNOW when it was last done! And assemble the pump/filter together OFF the car, much easier to do properly this way.
jp 83 Euro S AT 55k

Dennis Wilson

When you replace the fuse, make sure to get the ceramic type with the copper element like the 928 vendors sell. Since the fuses have a very small contact point/ring, the plastic with aluminum element fuses, like they sell at AutoZone, tend to corrode up very quickly.

Dennis

Ducman82

while talking to him on the phone, he was getting power at the T5 pin on the CE (to fuel pump). so the relay is working, but as to the right amount of juice getting to it.........