1999 Dutch Star F53 Idles fast and slow

[tderonne]

Is a ‘99 F53 one on the ones that needs the grounds redone to the PCM? That led to odd shifting, didn’t it? Almost sounds like the PCM keeps reinitializing. Grounding might do something like that.

[Waiter21]

Is a ‘99 F53 one on the ones that needs the grounds redone to the PCM?

I was thinking along these same lines. What would cause the PCM to constantly energize/de-energize the fuel pump relay....

The relay coil gets its 12 volts from relay 5. this 12 volts supplies a number of circuits. The PCM supplies a ground to the fuel pump relay to energize it.

SO, is it a 12 volt supply problem or a ground problem? I would put a meter on the 12 volt side of the relay coil and make sure its getting a good 12 volts.



The problem is, theres no room in there to have the relay plugged in and also take a voltage reading in the pin. May need to solder a small wire on the relay pin so you can read the voltage while its plugged in.



here is a link to the diagram on my web site:

http://1999southwind.com/DOWNLOAD/E1I02502.pdf


http://1999southwind.com/DOWNLOAD/E1I02503.pdf


and here is a link to the TSB for ECM grounding:

F53 – TSB Transmission shifting weird in 1st and 2nd gear – 1999 Southwind 35S


hook a scanner up to the ODBII connector and see if its doing anything weird..

Waiter21: what do you think of this idea. Since the the problem is a rolling idle with stalling, how about a jumper wire on the relay to see if the problem is with the fuel pump relay circuitry.

Yes. you need to be very careful when doing this. Basically, bypass the PCM ground and supply your own ground to energize the relay. i.e. solder a wire on the relay pin, then plug the relay back in to the socket, then ground the wire. the relay should energize.


Pins 1 and 2 are the coil. The pins I have highlighted in red are the actual contacts for the fuel pump itself.

[99DS]

Here's a link to the RPM video....

https://www.youtube.com/watch?v=x5mer2KJ3b0

[Mark_T]

DS99: you might want to call a dealer and see if this tsb was done.

[99DS]

Did anyone see the RPM video?

[Unplanned Tourist]

Originally Posted by 99DS

Did anyone see the RPM video?

I just watched it.

Have you disconnecting the wires off the throttle by-pass valve (IAC) and tried setting the idle speed manually with the throttle stop screw?

That would rule out that part of the system.

Happy Glamping.

[99DS]

Yes I did, same thing, then just turned it back. I am going to look at grounding wires today....

[Waiter21]

Regarding the clicking fuel pump relay, I've been asking myself: Is the clicking (fuel pump turning off/on) causing the fluctuating problem , or is the fluctuating causing the fuel pump relay to turn on/off. i.e. low rpm causing fuel pump to turn off.

The easiest way to answer this is to remove the relay and then use a jumper wire to jump across the terminals so the fuel pump runs all the time. Those would be terminal 3 and 5 in the relay diagram I posted.

[Mark_T]

I agree, but for safety sake I would use some spade connecters the same size as the ones on the relay. Run the wires out away from the relay box.


Could use spade connectors and wire and extend the relay out of the relay box. If you are careful not to short out the relay connectors you could measure the voltage on the pcm side of the relay.

Originally Posted by Waiter21

Regarding the clicking fuel pump relay, I've been asking myself: Is the clicking (fuel pump turning off/on) causing the fluctuating problem , or is the fluctuating causing the fuel pump relay to turn on/off. i.e. low rpm causing fuel pump to turn off.

The easiest way to answer this is to remove the relay and then use a jumper wire to jump across the terminals so the fuel pump runs all the time. Those would be terminal 3 and 5 in the relay diagram I posted.

[99DS]

I'll try that first thing in the morning, great idea!

[99DS]

Well, made the little paddle wire connectors.... AND never got to use them, started it and for some reason.... NO clicking? WTF

[Mark_T]

What about the idle?

[99DS]

Still exactly the same.... Geesh

[Mark_T]

Try bypassing the relay anyways to see what happen to the idle.