freddyuk

Hi all,

I was shown a trick to start my often flooded 928s2 (1985 auto UK car) by the recovery guy the other day; just pull the fuel pump fuse so it can breathe then try cranking it - hey presto it fires up, stick the fuse back in and away you go! On my car this is the 15a fuse 4th from the right, easy to get to. Maybe this will help someone in a spot.

Now I almost feel able to drive the car any time, all I need to do is forcibly contort my ageing carcass into the passenger footwell to get to the fuse box each time I want to go somewhere, or get home from somewhere, so quick and easy to do in the freezing wet British climate.

If I am going to keep the car (and not roll it off a cliff in a fit of pique), I must make sure to have a few spare 15a fuses...

Maybe, just maybe there is a way to figure out why the car is running so rich in the first place, I don't know where to start! No pun intended...

hwyengr

I learned this same trick the day I drove my 928 back on a 300 mile fly-in drive home road trip and got stuck 150 miles from home at a road side gas station. I was about to go for the $1000 tow until pulling the fuse and cranking.

freddyuk

It's a very useful thing to know! The recovery guy first of all took out the plugs, heated them, checked the gaps, checked for spark, checked fuel pump, then it dawned on him - pull the fuse - boom! What a relief! I just hate the feeling of being stranded and I fall out of love with cars very fast when it happens!

FredR

There is always a reason why these things happen- fix the obvious and stop it from happening- this list is bound to have folks who will advise you what the reason is. I do not know much about your model but assuming it is LH equipped have you checked that the temp2 sensor is transmitting correct resistance values? If a car starts OK when cold and has problems over fuelling when warm then there must be a good chance the brains do not know the thing has warmed up and will thus over fuel.

freddyuk

Thanks Fred,
is there a way to test it? It’s the thing on top of the water pump with wires sticking out I believe - will look on the WSM when I get a sec

FredR

Just check the resistance at different temperature values- more specifically ambient and at working temperature. This can be done on the sender itself or across the appropriate wires on the LH or EZ plugs.

Note the temp 2 sender has two pins - one for each channel and if you measure the resisitance for that sender it must be done from pin to external ground. The sender that displays temperature on your dash also has two pins but that is a single channel and one of the pins is ground. Not sure where they are located. Not sure where they are located on your model but persumably somewhere on the water bridge. Will try to post the temp 2 resistance values a bit later unless some kind soul beats me to it.

76FJ55

A leaking FPR or Damper diaphragm can cause hot start flooding too. While you're under the hood checking things, pull the vacuum lines on those and check for any fuel that may be making its way into the manifold via leaking diaphragm.

freddyuk

Thanks Fred, What is an external ground, please?

freddyuk

Thanks mate, I'll do that. Very little ongoing maintenance has been carried out on this poor old car so I'll check these.

FredR

The temp2 sensor grounds via the body of the sender so to get the values one has to measure the value for each pin to ground. Some folks make the mistake of trying to measure resistance across the two pins and get nowhere. The sender for the dash panel gauge is measured across the two pins but no one seems to know what the resistance values are for that item [background info].

The resistance values across terminals 23 and 12 of the EZ plug as recorded in my WSM are:
0C- 4.4 to 6.8kohms
15C to 30C - 1.4 to 3.6kohms
40C -0.9 to 1.3kohms
60C - 480 to 720 ohms
80C - 250 to 390 ohms

Once the motor reaches 80C no more adjustments are made as the motor is then considered "warmed up" even though it will typically run in the region 95C to 98C.

freddyuk

Cheers Fred,
I'll go through this then hopefully at the weekend, very helpful info from everyone, as ever! You guys are all great!

MJVirgo

That's a good tip, thanks for sharing.
Regarding your overfuelling have you tried all the usual suspects, coolant temp sensor, afm, fuel pressure regulators. Also worth checking that the injectors are the correct spec in case a previous owner has fitted some which are higher flow.

StratfordShark

The other day I measured resistance of the temp gauge sender. With cold engine and outside temp 15C it was 1100 ohm. Fully warmed engine it measured 120 ohm. No idea if that’s in spec, but I have new gauge sender coming and will compare. My gauge reads 2nd white line when fully warm so could be the sender resistance is below spec and driving gauge higher, though the gauge reading sounds variable from 1st to 2nd white line according to reports here.

freddyuk

Thanks for the info mate, are you in the UK? If so am wondering where you bought your sender from.

FredR

Is your dash panel gauge functioning?