77 924 Martini's alive! but need some help

[DMRK]

Well after a long nap (a couple owners long) we got my step sons 1977 924 Martini running again. She has some things to work out but seems to run pretty good.

First here's what has been done:
fuel tank removed and cleaned out
fuel pump was cleaned out as well
fuel line to filter flushed and new filter installed
cleaned all 4 injector lines with compressed air
cleaned and tested injectors and reinstalled with new seals
set fuel distributor to base setting
checked thermo time switch (failed infinite resistance when cold)
checked cold start valve using a remote starter switch (passed)
checked resistance of coil on warm up regulator (passed)
checked resistance of coil on auxiliary air regulator (passed)

Now here is where I could use some help:
She starts good when I use the remote switch on the fifth injector (new thermo time switch coming in the mail) for a few seconds to get her going.
Runs strong but idles about 800 rpm too much. Is this just a function of the bypass screw on the throttle body in combination with adjusting the fuel distributor?
After about 5 minutes of running there is a loss of power, it seems to bog down. My speculation is that when either the warm up regulator or the aux air regulator warms up and does its thing I then have an improper air fuel mix. Does that sound right to anyone? Any thoughts on how to proceed from here would be greatly appreciated.

Thanks, Dave

[phoenix_iii]

Congrats, good work. Pics?

[924RACR]

I would be suspicious of warm-up regulator, sure - do you have access to gauges to check it?

However, there are a couple of other things that cause high idle and poor running; #1, fix the vacuum leaks (which you will invariably have), and #2 check and adjust the ignition timing.

Additionally, yes, there's just the idle bypass screw on the front of the throttle body... that can be used to compensate for now, but you'll want to check/confirm/fix the above as well.

[DMRK]

Thanks
I'll check to make sure i am getting voltage to the bi-metalic strip on the WUR first.
I dont have a gauge that will connect to the banjo fitting.
Im sorting out and fixing the vacuum lines. According to the registry it is a CA car.

pics

[running_cold924]

talk to the guys on www.924.org and you will probably get a lot more responses from the older guys......thats where I turned for questions my my 24. It had dual mikuni carbs though, no fuel injection......

[DMRK]

Yea I thought of 924.org but I usually just post here, and as long as Vaughan Scott keeps posting here I'm good with it.

Ok well here is what I found this morning.

The voltage for the WUR and the AAR that comes from the fuel pump relay is good so I know my wires are ok. I have noticed that the insulation on the wires in the engine compartment of these 30 year old cars is very brittle to say the least.

I left the WUR unplugged and the engine did not bog down. So I think it is working, But I think I need to adjust my fuel adjustment clockwise. Does that sound correct?

Also I dont think the AAR is working which might be causing my high idle. Could that be? I will remove it and look to see if it is or not.

Thanks for all the help, I think I can have her sorted out in the next week or so. Takes awhile when it is an hour here and an hour there but thats ok.

[OnTheRun2]

Just a shot in the dark here but I would replace the O2 sensor. There are other problems involved, but It's worth a shot.

[924RACR]

Uhhh... these cars don't have O2 sensors, or electronic fuel injection to use that information.

The AAV and WUR will eventually warm up anyway; the electrical connections just speed up the process and improve driveability during the warm-up period. Eventually, once the car's fully warmed-up, you could disconnect them and have no noticeable difference on the way the car drives.

So yes, it is quite possible, if it runs well during the warm-up period but not once it's warmed up, that your base settings of idle speed and idle mixture are incorrect. They should always be set only when the car is warmed up fully.

Often to check the AAV, it's necessary to see that it's closed when hot, fully open when cold - and to get it cold enough, sometimes you have to remove it and stick it in the freezer! Cold right now, where I am, it'll be nearly all the way closed - 'cause I'm in Phoenix right now, ambient is 70-80 deg!

[OnTheRun2]

Ahh, Sorry half asleep wile posting. Didn't pay attention.

[DMRK]

I let the car warm up without the WUR electrically connected and after 15 min or so it did start to run poorly, it just took longer.

I will check the timing with a timing light to make sure thats all good.

I have also decided to buy a set of gauges to set this up correctly. Any ideas of where to find a good reasonably priced set at?

So what would be the proper way to set the fuel with the gauges?

Thanks for all the help guys!

[924RACR]

Drop in at 924board.org, and first of all see if anyone's near you and can lend gauges. There's also been some discussion there about the best/cheapest place to buy the gauges; I haven't been paying attention as I already have mine, but I think JC Whitney might now have the cheapest set. But check in there for the latest info; CIS systems require a slightly different gauge setup than a normal EFI system.

Oh, yeah - fuel pressure, specifically the system pressure you're having trouble with, is not adjustable. You will have to replace the warm-up regulator, if it's bad.

[DMRK]

OK, I ordered the CIS set from JCW. Should be here by the end of the week.

Does it make sense that if the WUR is bad it would start good but run bad after it warmed up? There must be something i'm missing here because its not making sense to me. When the WUR is warm is the valve completely closed?

[924RACR]

Yes, that makes sense.

Look in the Haynes manual for a detailed graph of the pressure the WUR should generate. You'll need it for your tests anyway.

[DMRK]

Yea I looked at that as I re-read some more.
Seems to run fine in the enrichened state with the WUR open, but when it closes it loses power. I think it is running lean when that happens. I have a feeling the fuel pump is weak, among other things possibly. The problem with that is it is different from the 771/2 on up, can I fit/adapt/upgade to the new style? It is alot cheaper and easier to find.

[924RACR]

Depends... the factory OEM Bosch pump, no, but some aftermarket pumps can be made to fit, like the Pierburg I think can be adapted... they're naturally made to be more universal.

I do agree, it is worth the trouble to adapt the later style, given the price difference! I think the biggest issue will be just fixing the fuel fittings; the electrical connections are easily replaced with ring terminals for the later pump. Perhaps, at worst case, you could swap in the hose that goes from the pump to the accumulators from a later car being parted out.

[DMRK]

Went ahead and ordered the $99 hopefully Pierburg (BECK/ARNLEY Part # 1528008) from RA. Cant beat the price and hopefully it is true to the pic.

I looked at the pump again this morning to be sure and it is the later style. I thought for sure it was the other style for some reason, but thats ok.

[924RACR]

I hope that's not the in-tank pump?

[DMRK]

I dont think so. It just looks like it is covered in rubber to reduce vibration and keep it quieter maybe. The fittings look correct. It looks like you can see URG in the pic. I found out about it by searching on the 924board.

[924RACR]

I tried to edit my post yesterday, but the network crapped out... yes, if it matches the picture, that is definitely the external pump and does look like the Pierburg (all covered in rubber noise insulation, as you say) vs the Bosch which is larger and metal, no noise insulation...

[DMRK]

Well, I checked the fuel flow per haynes (as I should have from the start) and to no surprise it is low. I am lucky if it gets 500cc in 30 sec. Fuel pump should be here very soon, got the gauges allready. Will check the pressures after the new pump is installed.