Cold start injector apparatus.....how does it work?

Can anyone give me a brief concise explanation of how those work? I am speaking of the ALH fuel pump.

NO, we don't need a 14 page thread here.....like everything else ends up being.....seriously.

Apparently, fuel is delivered through the side-port in the multi-stepped machined surface.....fuel goes through the screen and into the body of the injector body.....and then is delivered out the front with a very small pintle...which flows through that odd miniature half-moon slot????????

Does this then increase case pressure?

Or am I totally full of crap????
Thanks.

I don't have the diagram in front of me, and probably wouldn't give a clear explanation in spite of that. But the cold start solenoid advances the timing and is driven by the case pressure. It does not change the injection quantity, just the timing. That said, there is a limit to how much the injection event can be advanced. Also, the case pressure limiter/retainer mechanism (a small check ball under a spring) helps here. It could be that some people have cold start problems because sufficient case pressure to operate the solenoid is not available. But that is conjecture on my part.

Cheers,

PH

I'm not following your description.

There's the cold start solenoid that PH described but it's poorly named. It actually controls the timing at all times by cycling case pressure to move a piston at the bottom of the pump that rotates the ring holding the four rollers that the cam plate rides on.

Moving the the rollers opposite the shaft rotation advances the timing.

The cam plate pushes the high pressure piston that actually develops the injection pressure.

Case pressure is a function of the pump speed, the relief valve at the front of the pump and the restrictor at the pump outlet. It's not controlled directly.

Last question:
Is the signal to the device "graduated" or is it all-or-nothing (off or on)?

With only two wires into it......I bet all or not.

It is a pulse width modulated valve...controlled by the ECU.

Thank you.....aaahh.......thank you very much.

All of a sudden, I remembered why I hated university physics II. I gotta go sit down.

I'm probably going to derail this thread (I have a knack for that)...

In another thread there was a discussion about applying action to the accelerator pedal to assist in cold starting. Someone (maxmoo?) provided a link to the workings of the IPs but I believe that would not necessarily connect the dots (and I'm feeling a little lazy about putting myself up to read/study it); and, again, I'm kind of derailing here... Is this not acting upon the N108? In perhaps a futile attempt to link my question to this thread, how would the IP manage to react to this "pre-priming" (instruction to shift the N108?) so quickly (if the N108 is reacting to case pressures)? I cannot think of anything else being responsible for the claimed alteration in (cold only?) starting (not to be confused with the under-attribution of the N108 as the "cold start valve")?

For those who don't know...here is what they the n108 looks like.
There are no external moving parts like the fuel pump solenoid located at the top of the fuel pump.
http://www.kermatdi.com/n108-injection-pump-advance-solenoid-for-10mm-alh-injection-pumps/

They are not cheap. I swapped out with one purchased from a truly stellar guy here (Burn). Did not help me with the problem I am having.

Note to self: next time you buy a "project car" in another state, bring it home IMMEDIATELY upon purchase. Some sellers can't resist the urge to allow their pals to swap out defective parts while it takes you two weeks to actually pick up the car.

I realized the potential for something like this to happen was lurking....but, I hate to paint the entire society as corrupt. Whatever. My friend in Oho is sending out another pump next week. I did the same for him several years ago with a dinosaur pump.

Frustrates me as I burned up a new seal kit while the pump was off the car. The joker who swapped pumps actually broke off his timing pin and left it in the pump in his haste. And, I had actually driven this ticking-time-bomb about 100 miles trying to get it to run right.

Maybe years later....I will look back and laugh. Right at the moment it ain't funny.