Difficulty starting

[nwarner]

My 390SE has always been a job to start since I've owned it. It used to take about 5 seconds of turning the starter before it would fire when cold or hot. Now it takes well over 10 seconds to fire when cold and you have to leave it at least 15 minutes when hot before it will start (again after over 10 seconds of turning the starter). I've checked everything I can think of and tried a new battery, new plugs & leads but no change. It runs fine once it starts. Has anyone any other ideas I could try?

Thanks

Nige

[pjtvr390se]

Trying to narrow this down:-

Can you tell if the fuel pump starts to pump as soon as you turn the engine over?

If you let the key return to the run position before it starts does it run then, ie. after two or three seconds cranking?

[mrzigazaga]

Hi Mate..I had some serious issues with my 280 and it started exactly like that and progressed into flattening the battery while trying to start it..Mine was fuel pressure as my accumulator was leaking from the air relief valve at the back of it..Mine was found by clamping the pipe..(If you have one)..on the back of it that goes to the tank..If petrol seeps out from the rear of the accumulator then its that..Have you had your fuel pressure checked?..Have you checked for minor leaks?..Vapour lock?..Hope this helps..Ziga

[combine]

I put a new fuel pump on her in my ownership.

[350zwelgje]

If it is not what is already mentioned:

Do you get a fat spark when starting/cranking?
If not, would look into that the coil/amplifier and that the power to it is ok. While starting the voltage drops due to the starter sucking all it can and there is a mechanism to counter this at startup. All based on that once started it runs fine, which could rule out the coil as it could show problem once it is hot.....

Rob

[nwarner]

I tried your suggestions last night. This is what I found.

Fuel pump starts as soon as engine is turned over and the fuel pressure is fine.

After about 10 seconds of cranking it actually starts after I let the key return to the run position and not before. I had noticed that it started doing this a few months ago.

Nice fat spark when cranking.

[mrzigazaga]

This sounds familar to something that was happening to me..I would turn it over and it would just keep cranking but the second i let go of the key it tried starting..Try cranking yours for 1-2 seconds and then see if it tries to start when you return the key..At first i thought it was my ignition module so i replaced that..No joy..I then took out the ignition lock and replaced the inner coil..No joy..It was then found to be a wire that had worked itself loose from a connector further up the ignition wiring..Ziga

[honestjohntoo]

nwarner said:

My 390SE has always been a job to start since I've owned it. It used to take about 5 seconds of turning the starter before it would fire when cold or hot.

Now it takes well over 10 seconds to fire when cold and you have to leave it at least 15 minutes when hot before it will start (again after over 10 seconds of turning the starter)

If your 1987 car is a flapper - read on - otherwise just note the general principles of Efi set-up.

There are two issues here - I'm thinking that for the cold start problem your cold start injection system is compromised. You can read loads about the mythology of the system here and the basics of the CSI system from the Efi component index on the same site.

A lack of a rich mixture may be preventing the engine from firing until there are enough fuel molecules ingested for it to struggle into life. You might overcome the problem by booting the throttle to fire the acceleration and full load enrichment circuits to work around the problem.

Your later post

nwarner said:

After about 10 seconds of cranking it actually starts after I let the key return to the run position and not before.

also tends to support this analysis as the engine is not seeing any fuel from the CSI..

However the above does not explain why the engine dislikes starting from hot. For that you need to examine if the Efi system is set up correctly or search for other fault conditions.

Although is possible, I doubt that its due to fuel vaporization, there are too many easier issues to deal with first, so I recommend you do a full 15 point health check as detailed here

For easier diagnosis it would help to know the condition of spark plugs - one from each bank, at the least.

Reason for asking is that its entirely possible for cold and hot starting probs to be caused by flooding, usually accompanied by fuel smells and wet plugs, so more clues are also needed.

[pjtvr390se]

Another thing you might check before going down HJ2's full diagnostic route is the single black and white wire that leads from the ignition amp on the dissy and disappears into the wiring loom by the resistor pack on the inner wing. It has a push together connector near the resistor pack end and mine was breaking down causing intermittent rough running and poor starting, its purpose is to tell the ecu that the engine is firing.

[Wedg1e]

I'm still thinking that the cold start injector only squirts when it's REALLY cold. Even British summers aren't THAT cold...

[plushuit]

mrzigazaga said:

It was then found to be a wire that had worked itself loose from a connector further up the ignition wiring..Ziga

Yes. What if the ignition or some component is not delivering either spark or fuel in the starting/cranking mode?

To test for that, feed both your fuel pump and coil power directly from an alternate source. Then start the car up. If you start satisfactorily, remove one or t'other of the alternate feeds and start again. If the problem returns, you have picked the area to concentrate on. If not, it is the one you didn't pick.

[honestjohntoo]

Wedg1e said:

I'm still thinking that the cold start injector only squirts when it's REALLY cold. Even British summers aren't THAT cold...

True, but it squirts because our summers are never over 35 deg C either. The average is 20 - 25 deg C. Check this out.

• The thermotime switch contains a heater coil around bimetal operated
contact points, and works as follows.
• During cranking in cold conditions current can pass through the closed contact
points of the thermotime switch and cause the injector to operate. Simultaneously,
current is passing through the heater coil to warm the bimetal. After a maximum
of 12 seconds the expansion of the bimetal will open the contact points. The
injector then ceases to operate to avoid an over-fuelling condition.
• In any case the injector will cease to operate as soon as the engine fires because it
is only connected to the ignition system during cranking. When correctly tuned,
the engine will fire and run long before the maximum 12 second limit is reached.
• At higher coolant temperatures the operating time progressively lessens, until at
35°C approximately, the thermotime switch contact points remain open and the
cold start injector will not operate.

For anyone not familiar with the operation, the two components are at the top right of this image functioning off the WR cranking circuit.

[nwarner]

honestjohntoo said:

Although is possible, I doubt that its due to fuel vaporization, there are too many easier issues to deal with first, so I recommend you do a full 15 point health check as detailed here

For easier diagnosis it would help to know the condition of spark plugs - one from each bank, at the least.

Reason for asking is that its entirely possible for cold and hot starting probs to be caused by flooding, usually accompanied by fuel smells and wet plugs, so more clues are also needed.

I have gone through the 15 point health check and everything checked out OK. I have also removed one plug from each bank and they were both dry but you could smell petrol on them.

pjtvr390se said:

Another thing you might check before going down HJ2's full diagnostic route is the single black and white wire that leads from the ignition amp on the dissy and disappears into the wiring loom by the resistor pack on the inner wing. It has a push together connector near the resistor pack end and mine was breaking down causing intermittent rough running and poor starting, its purpose is to tell the ecu that the engine is firing.

Mine is fitted with a mallory ignition system consisting of Distributor, Coil and Hyfire control module but I will check the connections hopefully tonight, if not at the weekend.

plushuit said:

Yes. What if the ignition or some component is not delivering either spark or fuel in the starting/cranking mode?

To test for that, feed both your fuel pump and coil power directly from an alternate source. Then start the car up. If you start satisfactorily, remove one or t'other of the alternate feeds and start again. If the problem returns, you have picked the area to concentrate on. If not, it is the one you didn't pick.

I will check this tonight too

Thanks

[nwarner]

Just to let you now I finally found the problem at the weekend.

Because I'd flattened the new battery trying to start the car I put my sons battery from his BMW on as it was the same size and the car burst into life as soon as I turned the key. Charged the new battery overnight and put it back on and it eventually started after turning over for 10 seconds. Took battery back and exchanged for another and it starts fine now almost straight away.

Nige

[jmorgan]

Just wondering if you measured the old performance?

[nwarner]

jmorgan said:

Just wondering if you measured the old performance?

Not sure what you mean.

[jmorgan]

The battery. I its fixed now but just wondering. Had a non starter that once the fault was found (not the battery) it would start on a lower charge.

Better still, ignore me.

[mrzigazaga]

Hopefully its sorted ..But if it happens again check that your alternator is charging the battery...Ziga

[honestjohntoo]

Must admit, was a bit misled by your statement

nwarner said:

I've checked everything I can think of and tried a new battery,

but if the battery was duff from new then that would explain it, however I have a feeling this fault may return. Mr Zig may have pointed out the cause.

[adam quantrill]

The strong battery is covering up another fault. I would expect the (lack of) ignition to be the problem, it sounds marginal at best during cranking.

Now you have something that works, try measuring the battery voltage at the battery terminals while cranking (A) , and also the voltage from the ENGINE crankcase to battery +ve (B), and also from the distributor ignition +ve to the engine crankcase (C).

I have found that the ignition should work down to around 9V supply, below that it gets a bit iffy. If your supply or ground leads are suspect then you will see A being much greater than B, greater than C by a volt or more. If the leads are good then the voltage drop will be under half a volt.