280GE fuel issue
Hi,
I have just bought a 280GE and it has a running issue. The previous owner has fitted a new fuel filter and fuel pump.
I can get it to run fine for a short period by pouring fuel into the metering head flap area, but when that runs outs the G cuts out.
#1 The fuel pump buzzes for 2-3 seconds when you turn the key (as it should)
#2 There is a click from the dash which I believe is the relay
#3 I appear to have fuel to the metering head
#4 When I cracked off the injector feed pipes from the metering head they all show fuel.
I have now checked the pump and it also buzzes during engine cranking, which leads me to believe this is not the problem.
Given that it runs on fuel directly applied I put this down to a fuel supply issue. Can anyone advise on how to test/what to look for?
Hi The Bosch Jetronic mechanical fuel system as fitted to your G' is complex..go into your search engine and enter as described above and study for a bit..the high failure item is the cold start regulator...but if it ran before the fuel pump and filter was changed and you are getting fuel to the "seventh injector" could be that one of the many vacuum pipes is perforated or detached robbing the air sensor of suction...not easy to sort out without awareness of the system.....the pump will run as you turn the key on and stop after 3or4 seconds...when you turn to start it wll run continuously once the engine has started.rpm should indicate 1000/1200 rpm at cold start slowly reducing to 700rpm when hot...at every hot start engine should rev to 1000/1200revs for 5 to 6 seconds and drop to 700revs at idle ....hope this helps rgds Peter
sounds like the relay
sounds like the relay
Surely not - its a new relay. When I turn the key till the lights come on the fuel pump buzzes. When you crank the engine it also buzzes.
Even if I bypass the relay by bridging pins 30&87 it still won't run.
Hi Did you look at the accumulator ( close to the electric fuel pump in front of the fuel tank... could be part of the problem....if the pump is loud enough to hear from inside the car it could be starved of petrol.(kinked or collapsed hoses) when you say it runs when your pour petrol into the air sensor ( a fitting under the metal pipe that goes to the airfilter with a floating plate in it that should be closed and only moves when inductiion air is being drawn in) does it just rev out and stop with lots of black smoke?.....
Having had a friend now turn the key while I check the fuel flow its become apparent the pressure to the fuel distributor is woeful.
I'm left to believe its down to poor/blocked fuel lines or a duff accumulator. Has anyone had fuel flow issues with the accumulator before and if it is bad where is best to buy a new one?
Can it be bypassed to test the engine?
Hi Did you look at the accumulator ( close to the electric fuel pump in front of the fuel tank... could be part of the problem....if the pump is loud enough to hear from inside the car it could be starved of petrol.(kinked or collapsed hoses) when you say it runs when your pour petrol into the air sensor ( a fitting under the metal pipe that goes to the airfilter with a floating plate in it that should be closed and only moves when inductiion air is being drawn in) does it just rev out and stop with lots of black smoke?.....
The pump can't be heard from inside but can from outside and its not noisy.
If I pour some fuel into the air sensor (plate partially open) and then crank the engine after a few seconds the engine slowly picks up revs, ticks over and dies when the fuel runs out. No drama, no smoke - just cuts out.
I'm beginning to think its an issue with the accumulator or a blockage. I don't actually know about the accumulator and how a fault on it may affect fuel flow but the main fuel pipes look corroded on the outside (no leaks though) and are therefore probably ripe for blockages/rust.
Can I replace them with new copper lines front to back and eraadicate any issue there?
sorry I was under the impression that you had by passed the relay and had flow, another possibility is that the pick up in the tank is blocked or partially blocked, tanks the age of your car are invariably corroded usually from the top down.
It's very easy to check whether you have sufficeient flow rate from the pump. Disconnect the reyrn line from the fuel distributor and connect a flexible hose to the threaded section. Start the pump and it should deliver 1L in 30s. (from memory) Obviously pump it into a can.
Replace the filter first, then the fuel pick up in the tank, the accumulator last if you don't acheive the flow rate.
Hey guys,
Great advice. I'll try the return pipe flow trick tomorrow and see what the results are.
As you claim, when fuel is poured into the plenium chamber it gets the engine started, for the moment we can rule aside an ignition fault. Concentrating on the fuel problem, you have indicated fuel to reach the injectors but that can be mis-leading. You ideally need to check for fuel pressure. The K-jetronic and similar genre of injection systems have an operating pressure of around 3 bars.
Check the fuel flow rate as per Roly's describtion, you should be able to collect approx. 1 litre of fuel per 30 seconds of runing the fuel pump by bridging the fuel pump relay. FURTHER MORE, and most imortantly, try and put your thumb across the disconnected fuel feed pipe to get a feel of any fuel pressure. If you are able to stop the fuel flow without difficulty, the fuel pump should be suspected. If the fuel presents some resistance even to a point that blocking the fuel off with your thumb pressure is not enough to block fuel flow at the end of the fuel hose, you have a healthy pump. You will need to turn your attentions to the metering head.
From where you disconnected the fuel feed pipe, in the metering body should be fine gauze filter, remove and clean as necessary.
Ideally you need fuel pressure gauge to diagnose faults at the metering head. This a piece of kit that cost some £300.00. Most independant garage do not ordnarily carry this kit, so I do not supose you will. Here, all I can say is pass the job on the a professional fuel injection specialist, i.e. Bosch agent garage to do the prognosis fo you. Faults could lay with fuel pressure regulator, fuel metering head or some one tampered with the fuel mixture screw. Ohh, note also, when attempting to crank the engine, with the air filter cover to the metering head removed, does the air mass sensor plate fluctuate to travel downwards or is it static? With ignition turned on by an assistant, as the fuel pump primes its self quickly check to see by pressing down on the air sensor plate if any resistance is offered. There should be resistance. A side line point in your comments earlier, bridging the fuel piump relay only primes the fuel pump, you will not get the engine to start just by bridging the relay and cranking the engine , the relay has to be connect as that is part of the ignition ciruit.
Let me know with more feed back as to your findings.
Good luck.
I did a fuel flow check at the metering head as advised with the fuel relay bridged. Rather than the expected 1L of fuel the result was around 50ml .
I didn't even bother with a finger pressure test - it was evident it would be virtually non-existent.
So I spent today checking the fuel supply from the metering head back.
I began at the outlet from the fuel filter as it was an easy one to access (and would point to the accumulator if good flow was evident) which showed pathetic fuel delivery.
The same was found the inlet side of the filter which leaves me with the piece of pipe from the fuel pump, the pump itself and the tank.
I note the fuel looks yellow (like pee!) and information from the last owner reveals the car was stood for nearly 3 years. Perhaps bad fuel clogging things up?
Well, I managed to get the tank removed today with the help of a friend. Some WD40 on the tank strap bolts overnight and we set to this morning - into the unknown.
Firstly the first tank strap bolt snapped. The second one luckily stayed intact despite the force it took to remove the nut. I'm going to grind both off and replace with coach bolts and new nuts.
I removed the pug from the sender and cut the upper pipework as it was looking overdue for replacement and I didn't fancy damaging any metal inlets/breathers on the tank.
An hour wrestling with a jubilee clip on the fuel filler and the tank was removed, with pump in situ.
I drained the fuel which was brown/yellow. I've removed all clips and rubber hoses now - I plan to replace the lot with new ones front to back before it goes in.
The pump filter shows rust particles and gunge. The same black, tar-like gunge is evident on the floor of the tank. At first I thought it was rust but its more like a bitumen substance and seems to come off with a wipe.
What's the best way to flush the tank effectively?
Can anyone recommend a good replacement for the hard fuel lines/unions?
Hi the tarry substance is generated when petrol is allowed to evaporate..it becomes petroleum residue..to flush the tank first remove the fuel guage sender....use heating oil (2 gallons)in the bottom of the tank and soak overnight then empty through the filler neck.. do the same again(1 gallon) only shake the tank viigorously side to side and longways then empty...(best done with two people)...repeat until flushing liquid becomes clear. there is a very good chance that when all the residue is removed the tank will have become porous...specialist tank repairers up and down the country will line it and coat it (at a cost) a new tank from MB is GBP 400 +....secondhand tanks can be suspect.you must use petrol quality hose and fittings but you will probably need to purge the steel pipes along the chassis by pumping heating oil through them with a pump oilcan until the fluid flows clear.. new filters are a must and the accumulator should be changed to ensure the whole system up to the distributor head is clean..to finish the job fuel lines in the engine bay and to the injectors must be purged along with the cold start regulator....you might try running the engine after cleaning the plumbing along the chassis but chances are you will have to do the rest of the system to get the engine running properly... be methodical!! if you miss a section the pump pressure will push the residue into the filter at the fuel distributor head. ***All seven injectors will have to be removed and serviced...
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I've already done that.
The fuel pump works, static and active (pressurising and cranking).
Fuel is getting through the distributor to the injectors.
By pouring fuel direct the engine runs (until the fuel is exhausted).
When the fuel pump is continuously running (but by use of a jumper) fuel pressure is evident, but seems to be 'flowing' rather than under heavy pressure.
After continuous operation for a few minutes, cranking the engine produces a 1-2 second attempt at starting and then nothing.
Loss of initial fuel pressure?