1979 245 with Kjet.

the car will start when starting fluid is sprayed into the intake manifold, (thru the hole that the flame trap hose uses).

but when i try to give it gas, the car bacfires out the intake system. out to the air hose.

any thoughts on how/why this might be happening?

yes, firing order is correct.

and for the breif few seconds when it runs with the strarting fluid, seems to be running smooth.

thanks in advance for any help.

K-Jet systems need to be air tight and not allow any air to sneak by the Air Flow Sensor Plate or you could have horrible backfires through the intake. Another thing to check out is the Lambda Sond System (O2 Sensor System) ground points that are on the intake manifold. There should be about 2-3 ground points on the intake manifold that you need to unscrew, clean up, and resecure tightly in order to ensure a good ground point for the 02 Sensor System. I had a loose ground point on my 79 264GL after an engine swap and I had the SAME symptoms you are describing. It is worth a shot and it will only cost you some of you time. Let us know how it turns out. Take Care!

Sincerely,
--
Julio Meza

1979 264GL B27F 128K --> BW55->M46, CLS, IPD Sway, 81+ Dash, Gauges, Flat Hood & E-Codes

1979 262C B27F 166K --> Restoration Project

1984 245DL 218K --> Sport Wagon

2002 Mercedes C320S 40K --> Wifemobile

yeah, well, going to have to take a close look at the dreaded black boot.


that monster is sure fun to put on.

I might have damaged it when putting it on last. or at least hurt it's feelings by swearing at it so much...

I usually rub a little hand cleaner around the inside edges of the rubber boot before re-installing it. A little lubrication makes it much easier to put on.
steve

okay, thanks.

interesting, I tried having someone start it with my hand over the air inlet, and it almost wanted to start. i could feel the air suction.

and yet, it seemed like it wanted to start when it was getting less air.

weird.

First, make sure that the fuel pumps are running. Also check the big rubber bellows where the intake connects to the fuel unit. It may have backfired and blown it loose. Hope this helps
steve

thanks for the advice.

just put a new used pump on.

but hey, mayb it just failed.

I'll check the return line.

this car was not running for about a year of so, so I ended up filling techron in the fuel filter to get every thing unclogged, as it was only running on a couple of cylinders. and that did the trick for a few months.


I just put that rubber boot back on (what a pain). and it was running for about a month or so.

I have a couple of wild theories.

First thought on backfiring is that timing belt has jumped a notch, but that doesn't explain relatively smooth running with starting fluid.

Intake manifold gasket leak will cause minor popping, but the car starts and runs.

How about working the theory that the bulk of the starting fluid is not going to the problem cylinder, so it doesn't give serious trouble until you feed fuel/air to the problem cylinder? That would lead me to look for an intake valve that is hanging open (check compression) or a spark that is hitting early (check for traces under the distributor cap).


So this thing will not start at all unless you use starting fluid?

Curious.

the car will give the indication that is going to start, maybe just an idle for about 2 seconds, then die. and die imediatly if i give it gas.


now after that happens, next time i try to start it, it gives no indictation that it will start at all.


unless i wait for about an hour or so.


thanks for any help.

okay, well, i do have an adjustable cam gear. so maybe i should check that.

it has a K cam, and i think it was moved a few degrees in the direction that would make it have a bit more low end power.

but had been running just fine like that.

Wow. These puzzle pieces just aren't fitting together at all.

Try a few basic tests -
Plenty of fuel delivered at the rail?
How do those spark plugs look? Has it flooded?
I'm not familiar with your injection system, but on the later systems, another test is to see how it is affected by unplugging the airflow sensor. I'm guessing that on yours, the airflow sensor might be connected mechanically, so this might not be a viable experiment.

I'm fresh out of amature guesses. You need help from someone who actually knows something.

There's not a fuel rail as such, but individual lines to each injector from the fuel distributor. Pull that bellows off and after cranking a moment, try lifting the air flow plate and see if you hear a chirping sound from the injectors. (First - will the plate lift? If not, or it moves stiffly, your control pressure regulator is probably faulty.) If the plate lifts & the injectors don't chirp as they crack open, pull one out & see if there's any fuel spray. Crank again for a moment before doing this, to pressurize the fuel system. If there's no fuel, and the metering plate is moving freely, your pump is almost certainly at fault, not giving enough pressure to open the injectors. The reason it starts & idles for a moment is because on first startup, cold, the cold start injector is providing a brief shot of fuel. You really need a fuel pressure gauge to accurately diagnose K-jet though, don't buy new parts until you've done a proper pressure test. However if you can get a known good junkyard fuel pump & CPR, keep them on hand, you will need them eventually.
--
Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf, 90 740 Rex/Regina