Engine stalls
My 87 280GE starts and then dies shortly after. You have to "set" the ignition (turn it on without starting, then off) between 4-10 times to get it going again. This will happen between 2 and 5 times untill it reaches the correct running temp then runs all day fine as long a sit doesn't get cold again.Seems worsre on colder days ! Am i right in suspecting the Bosch Warmup Device ? It's had the vac lines all checked ,new inlet manifold gasket,fuel pump, filter ( cut open and clean inside ).It's smellie when running cold and seems to be only doing about 12 mpg ! Help ! it's driving me mad.
cold start injector?
no it enriches the mixture when cold to facilitate starting
I would think that it's working ok as the revs go up to 1200 when you start it. But after a little while it conks out as though you turned off the ign or it ran out of fuel. if you then "set" the ign 4-6 times (sometimes 10 times ) it starts again. It behaves as though it's getting air in the fuel line,but the problem goes when it's hot .
Is ther eany way of testing the cold start injector ?
only by swaping it with one you know works, you could take a chance with one from a scrap yard, they are plentiful being used on a huge number of cars in the 1980's. Or you could take it to your nearest Bosch Fuel Injection specialist.
Ok. Thanks . i am away until April so will have to wait till then. Do you happen to have the part No? many thanks Rob.
Hi the cold start regulator is bolted to the side of the engine block and senses the water temperature in the engine..with a bi metal strip..so when the engine is cold it opens the fuel flow to the seventh injector and as it senses warmth it closes the extra fuel off.it also has an electrical link to a sensor in the cylinder head above the EGR valve / exhaust manifold....either if faulty will give problems. the fuel system is pressurised and when you switch the ignition on you should hear the fuel pump run for 1 or 2 seconds..engine idle at cold should be 1000/1200 rpm reducing to 700rpm after a few minutes depending on the ambient temperature.when starting hot the engine should rev to 1000/1200 rpm for 5 seconds and drop back to 700rpm constant ..no smoke and running smooth enough to stand a glass of water on the rocker cover without ripples...the air mass sensor is fine tuned with a 3mm allen key and the idle speed is adjusted with a white plastic slotted screw below the distributor body----only very fine adjustment of either or both is required ..... FINE TUNING may well cure your problem!! try it first....
Fixwin38 Thanks for the tips. I have been through most of this before by looking at the threads on here.But i will go through it all when i get back . One other problem is that i have the hot idle at 900 as the oil warning light comes on at tickover when in gear. Have replaced the sender unit for the oil prisure and it's just the same. When it does cut out it's very hard to start again sometimes it takes 3-5 minutes ! Thanks Rob.
Hi are you using synthetic oil??....10w 40 mineral oil for these old engines....get the oil pressure checked ASAP because it could be much more serious--and expensive.....if the fuel pressure drops for any reason you will not be able to start the engine..try switching the ignition on and off 5 or 6 times before turning to start..this will build the pressure up again......you shuuld hear the pump run every time you turn the key....
Not sure whether to chip in with my 2 cents, but I did have a similar problem which got fixed by replacing the overload relay. You can test the fuse, but in my case the relay was broken.
Do not unplug and plug in the cold start injector power while engine is running it can damage relays/ecu.
Fixwin38. It's still got the oil it had when i bought it ! Will change it when i get back. Switching the ign on and off as you say is what i have had to do when it conks out !You hear the pump run every time. Could it be the fuel acumulator ? But if so why does it only stall when it's cold ?
Thanks Rob.
Hi Andy. That sounds interesting, do you know where it is ? Which one it is ? Thanks for the tip on the cold start injector .
Thanks Rob.
Hi the problem appears to be linked to the cold start sequence.it could be that you suffer loss of the correct cold start fuel / air mixture immediately after the first cold start. when it eventually starts the second time does in run rough and smoky? and then stop...will it rev during this period? if you have a vacuum leak anywhere at all in the system the mixture will be wrong and the air mass sensor will not operate correctly making the mixture too lean to run correctly when cold..but run ok when warm....follow ALL the small grey anf translucent vacuum pipes around the distributor... underneath the inlet manifold... even the pipe to the gearbox modulator (auto transmission) any split or crack in the plastic of rubber pipe interfaces is enough to put the whole system "off song"....
Hi fixwin38. thanks for the tips, i will try all that when i get back in April, it did have the vacuum system checked by a garage as there was 2 pipes not connected. I will go through it all again including the box pipe. Will let you know in April. Thanks Rob.
Hi Rob, the overload relay is under the steering wheel on the back of the fuse box, you remove the fuse board and then it's easy to remove/replace. It provides power to the idle air control, that's why it can reduce your tickover enough to cause stalling when cold. Try removing the connection to the idle air control if no change in the idle speed try the relay.
Well I finaly found the time to spend a day on it. Checked everything again, swopped or replaced the cold start injector, air acumulator device, inlet manifold gasket,checked all vacuum lines and conections, swopped the fuel pump relay,checked the thermotine switch resistance cold and hot it was within 10% of the figure i found for it . It's just the same. Starts Ok when cold but then cuts out won't restart unless you leave it for a minute or two then it restarts ok runs for a minute or so and cuts out , may do this 3-4 times before it warms up and then runs Ok all day ! ! ? ! ? Amazingly irritating ! Is there anything that's part of the ignition side that is only common to being cold ? Heeeeeeeelp Pleeeeese !
Hi if the engine does not start COLD on the first turn of the key with NO THROTTLE pressure and if the idle ""NO THROTTLE" revs do not run at 1100/1200rpm as soon as it starts then the seventh injector is not working.hence the short run and then stop. when it is hot and you start the engine you should get an instant rev to 1100/1200rpm dropping to 700/800rpm within 3 seconds still no throttle...the air mass sensor must have 100% vacuum efficiency to mix air/fuel correctly...you do not mention the cold start sensing probe in the cylinder head just above the EGR valve on the exhaust manifold.. if this is not sensing the cold start regulator will not function so no seventh injector supply for the cold start higher rpm.....
Hi Peter.
I think you might have got it as sometimes the revs kick up straight away and sometimes they don't so something seems very eratic. The cold start sensing probe seems the most likely suspect. Is this the one with one connection next to the thermotine switch ? I will go to my local mercedees stealer in the morning and order one. Many thanks Rob.
Hi One sensor is for the water temperature guage and the other for the cold start regulator..check also that the wires are good as they can go to earth or open circuit as they get older....
Hi Peter.
I had previously checked and repaired some of the wireing there as it had gone brittle and lost it's outer insulation. I think it must be the one with 2 connections known as the thermotine switch, but i will check with the agent and order the correct one in the morning. Will let you know what happens. Regards Rob.
Ok Peter.
Went out this morning, turned the key waited 2-3 sec for the pump to stop,no throttle and turned to start. It fired and ran at about 800 revs then over about 45sec climbed to 1000 after about a minute it coughed and missed a couple of times then stalled. Started again easily (still at about 1000 stalled a couple more times started easily and then ran fine. Just come home and made a coffe and emailed you went out put the key in waited for pump, turned key,fires at about 700 climbs to 1000 for about 1 sec and settles back to 800 running fine. When i swopped the 7th injector it was for a used unknown one. So presumably that leaves me with the sensor,injector or the wireing ? Any more thoughts ?
Thanks Rob.
hi from your description of events the seventh injector is working but your airmass sensor needs adjusting.the engine is stalling after the cold start sequence has completed its cycle... to adjust the airmass sensor you need a three mil allen key and looking at the top of the fuel distributor (thing with six metal pipes coming out of the top) between it and the duct that goes across the engine to the air filter you will see a 5mm vertical tube ..put the allen key into this tube and press down until you feel resistance when you try to rotate the key... clock wise rotation 1mm at a time will lean the mixture.... anticlockwise will richen the mixture.....adjusted correctly when the engine is hot it should idle at between 700/800 rpm and very smooth...no vibrations..... there is an idle adjustment facility located low down at 2 O' clock when you look at the top of the ignition leads /distributor cap in the form of a 5p sized slotted grey/white screw.... clockwise rotation slower .anticlockwise faster.....
I think at long last i have fixed it ! ! I checked the earth straps and there is one from the engine to the chassis,battery to bodywork and a small one from engine to bodywork, I could not find one from the chassis to bodywork so fitted one and" touch wood " she has run perfectly for the last 2 days ! I still don't know why the engine was cutting out but at least it's finaly fixed.
1:disconnction of lead
2:correct lead order
3:destoributer and pick up check
4:timing ajiustment
My 1987 280 ES SWB auto - owned by me as third keeper for five years with mileage of 57,000 - developed a variation of this one night last week - oddly right at the end of seven weeks' faultless performance in sub zero ++ temperatures. It started and ran normally for 10 minutes then cut out without warning when approaching a roundabout - but started immediately and completed the remaining five-minute journey without further trouble. It was then parked for four hours and again started normally, only to stall four times over the next 10 minutes, after which on two occasions, it was reluctant to start straight away. It seemed to improve after back-firing loudly and restarting itself on the last occasion, since when it's run without stalling -both when started and left idling for 20 minutes (twice) and under stop/start working conditions when moving trailer loads of hay over short distances, over a three hour period.
My mechanic thinks it most likely that there has been ice in the tank that got into the fuel filter. Has anyone had a similar experience and would they agree? Also, does anyone know the make/part number for a replacement fuel filter and where best to get one.
Many thanks. Xtn
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That's the 7th injector isn't it ? Would that give the affect of getting air breaks in the fuel system ?