Help please. W115 not starting after hose replacement. Injector lines seem empty. - PeachParts Mercedes-Benz Forum

bipolardave · #1 12-19-2011, 08:01 PM

I was just out replacing some fuel lines on '74.

I replaced the clear fuel line and banjo fittings at the back of the IP. This runs from between the block and the backside of the IP to the top of the fuel filter canister.

I also replaced the short angled part metal/part rubber line that connects the intake side of the hand pump with the small fuel filter.

In order to tighten down the line to the back of the IP, I had to remove the front two fuel injector lines.

Anyway, once everything was back together, I used the hand pump to fill the clear lines and kept pumping until I heard fuel squirting back into the gas tank.

I loosened the front two injector lines and cranked a bit, then retightened.

I've glowed and cranked several times and it's not even trying to light off.

On a hunch, I loosened the back fuel injector line and nothing shot out when I cranked it.

The car started fine yesterday. Glow plugs are working and I had a fresh battery installed yesterday.

Just a hunch, but is the relief spring (the spring that regulates fuel pressure) in the banjo bolt that I removed (between the IP and the block)? Would it's absence "short circuit" the IP and not allow fuel to be delivered to the injectors? I dropped that particular bolt several times and could have lost whatever may have been inside.

bipolardave · #2 12-19-2011, 09:12 PM

Update.

On a hunch, I undid and reconnected the fuel line at the hand pump. It was probably crossed threaded and may have been sucking in air.

I pumped it again and refilled the IP with fuel.

I managed to get it started, but it runs like crappola. It seems like it's idling at low idle despite being set to fast. Dropping it to low idle causes it to stall as does putting it in gear.

Another question: It is my understanding that the hand pump should not force fuel through the injector hard lines, correct?

For what it's worth, when I loosened #1 fuel line and pumped the hand pump, fuel was gurgling out at the injector. Could I have knackered the #1 delivery valve on the IP?

vstech · #3 12-19-2011, 09:50 PM

ok.
loosen ALL nuts on the injector lines at the injectors.
crank the car until totally clear fuel is out all injectors and then tighten them up.
start car, and report back.

bipolardave · #4 12-19-2011, 09:58 PM

Quote:

Originally Posted by vstech

ok.
loosen ALL nuts on the injector lines at the injectors.
crank the car until totally clear fuel is out all injectors and then tighten them up.
start car, and report back.

Thanks.

Yeah, I know there's plenty of these types of posts. They always boil down to air in the lines and, with enough cranking, they eventually take care of themselves.

Fuel leaking at #1 injector while pumping by hand made me think that I had something else going on. I didn't think that the hand pump pressure should reach the injector.

bipolardave · #5 12-20-2011, 12:00 AM

I can get it started but it still idles rough. As I loosen each hard line I get fuel squirting from each. It will stall unless I rev it while loosening.

I can see some small bubbles periodically in the new line I replaced.

Another possibility: it was going into the shop this week for new hard lines from the tank to the engine compartment. There was some weeping beneath the car so I was going to have that taken care of.

Assuming there's a leak in the hard lines, either supply or return, why would it run fine before but won't now after I've opened up the system?

I had all of the fuel injector lines off last summer performing an IP timing check and didn't have any problems whatsoever getting the air out of the lines. This is frustrating.

bipolardave · #6 12-20-2011, 05:15 PM

#1 delivery valve was loose. It became untightened while I was fidgeting with the hard line.

1. Keep those spline locks tight! If one's missing, replace it.
2. It's always the simple things.