hard starting hot with CIS

Fritz,

When you run the fuel pumps, do you run them until the sound changes?

Tony

 

Can you please clarify your warm restart symptom -- is it:

1. The starter motor cranks the engine over, but the engine never fires, or

2. The starter motor does not crank at all? (I realize it's probably #1, but I just want to make sure)

Does this mean that you confirmed that ignition is occurring during the no start starter motor cranking period? Pre-pressurizing the fuel system and not getting some help would make me suspect ignition.

And are you confirming that you hear the fuel pumps running with the saftey switch unplugged?

 

CIS have problems with fuel pump check valves and fuel pump circuits at harness plugs on back of fuse box. Both these problems usually are aggrevated by vehicle heat. Fuel pumps can be tested by checking fuel pressure right after shutting the pumps down,if the pressure drops emmediately , the check valve is bad. When testing make certain right and left banks are isolated. Also check plugs on back side of fuse box for any signs of excess heat at connections.

 

The check valve is not the only place were pressure can bleed off. Both the warm-up regulators and the pressure regulator valves in the fuel distributors can bleed off pressure when the engine is shut off. However the fuel pump check valve is the most suspect part that usually fails.

 

Just trust me on this....

Roll back the relay board. When you're looking at it flipped back onto the pass. side floor there is a tall black relay at the lower right. This is the source of your trouble. If this relay isn't clicking, the car won't start. It is double the height of the other relays and has nothing to support it. It gets lose and stops making contact.

 

Oh my! Look at that!
Anyone else have a board that looks like that on a 1982 car?

 

Mine is an 83 and it doesn't look like that. The front side is all fuses and relays. Haven't looked at the back. Maybe that is a replacement, something that wouldn't be unusual given the propensity of the stock board connections to have problems with heat and meltdowns.

John

 

looks like my beta tape player!!!

 

OK, back on track, Dave may be right and its your starter relay, but I don't know which one it is on your board. However, I suspect your fuel accumulators, when you run the pumps (try running them a little longer), do you get a change in sound or pitch after the pumps run for a while. Are you test running the pumps with the car in its hot no start state?

It is possible that your accumulators are not holding pressure and you are getting a heat soak situation where the fuel in the part of the system under the hood is vaporizing and pushing the fuel back into the tank. The accumulators are supposed to hold pressurized fuel and prevent this from happening.

When the pumps run on an unpressurized system, the sound they make changes when the system pressure is brought up.

Thanks, Tony

 

Fritz,

Congrats, glad you got it fixed. Next time you are in Reno, look me up and we can have a beer in the garage and talk silly cars.

Tony

 

My car developed a pb : start the engine once hot is quite impossible.
I showed the mechanic the above Dave's text that I had printed from the web.
As recommended by the wizard, the mechanic decided to check the black relay connection : bingo, the relay lived its own life, totally unplugged. Plug, start perfectly.

Thanks to Dave and to all the contributors.

By the way, my contribution would be :
The car went to the workshop because of two issues : difficult to start (solved as said), lack of power.
The latter issue has an explanation :
Once determined the side, (left side) it turns out the Bosch fuel pump is weak.
Throughout, this fuel pump is brand new (450$).
When asked, the Bosch dealer said the pumps come from Czeq rep and the quality is low :b he knew of many cases where new pumps should be replaced.

Second contribution :
Apart of Bosch, there is another maker named Pierburg that provides with fuel pumps. The ref is 7.21659.72.0.
I bought one, it works well. A difference is that Pierburg are fitted with a fuel filter, which can get dirty and reduces the fuel pressure. Bosch do not have such filters.
On both sides of the car, there are filters down the way to the engine, so the Pierburg filter might be useless.


Olivier

 

My pleasure, glad you got it fixed.

 

My 83 has essentially the same setup as my ex-TR (not good news), which is nothing like the pic shows.

 

Is this the same for a 1984 car?

 

Not if you have push-in fuses which I believe you do.

 

Correct. Here is a pic of my fuse box
Image Unavailable, Please Login

 

You can plainly see you don't have the relay I mentioned.

 

Sorry by the way. On a S1 car its almost always that relay which makes it pretty easy. On an S2 car it can be a number of things but it is still likely related to a fuel dump..

 

The first picture is the ‘79-82 (early fuse box). Essentially the same as fitted to carburettor cars with an additional few relays (4x) set off to the right. This sub assembly is exclusively for the K-jet system. 2x fuel pumps 1x start control, Red stripe and one for warm up system.
The later fuse box uses the multi-plug system and not quite as robust under heavy loads…