Not Starting

[RCK974X]

It's only a couple of bolts to get the cold start injector off .... and possible but fiddly, to get one of the main injectors out from under the airbox/plenum.

I reckon you should be able to smell petrol at the exhaust pipe after a few cranking attempts....just another idea to go with checking the plugs.

[jeff m2]

Get an in line spark plug tester from Advance Auto or other car parts chain, they are only about 15 Bucks. (Gives definitive result)

Put it between the center terminal and the HT wire.

If it glows orange put it between a plug and its HT Wire.

If no glow, pull plug on the amp module, clean, dielectric grease. re-plug.

Retest spark on plug lead.

If you get glow on the center but not on a plug it's your dist cap center.

[Grady]

RCK974X said:

It's only a couple of bolts to get the cold start injector off .... and possible but fiddly, to get one of the main injectors out from under the airbox/plenum.

Yes, that looked fiddly at best. There doesn't seem to be an easy way to do it.

However, with the engine off but the fuel pressurized, I cracked 3 of the banjo connectors around the top of the meter head and got differing flows from each based on how high I opened the plate. Which suggests the meter head is functioning. I'm hard pressed to think all 6 injectors packed it in at once.

RCK974X said:

I reckon you should be able to smell petrol at the exhaust pipe after a few cranking attempts.... .

And it did smell a bit when this non-start problem stated weeks ago, not so much now.

Edited by Grady on Sunday 27th September 18:19

[Grady]

Jeff - I picked up a tester and got good spark off the HT lead and the plug wires. That pretty much confirms the spark side is OK.

Thanks for the tip on the tester, much easier than my clip-on grounding one. Grady

Edited by Grady on Sunday 27th September 18:12

[jeff m2]

Grady said:

Jeff - I picked up a tester and got good spark off the HT lead and the plug wires. That pretty much confirms the spark side is OK.

Thanks for the tip on the tester, much easier than my clip-on grounding one. Grady

Edited by Grady on Sunday 27th September 18:12

You are going to have to pull an injector.

Pulling the cold start injector could be very misleading because depending on your Texas temp the thermotime switch could say "NO" due to it thinking the engine is hot.

I'm reluctant to suggest a squirt of ether in the plenum because it can cause quite a decent backfire on CIS (plenty of blown air boxes on 2.7 Porsches)
On a 280 it could blow the hose from plenum to air filtre. (and if you remove the hose the plate will not lift.)

So....injector it has to be.

If you get nothing or weak spray from an injector it points to the metering head, which of course is bad news, but you could give it a triple dose of Injector cleaner and hot wire the pump. With the pump running crack the pressure reg and waste some fuel. then try to start. Could get lucky.

You could also crack one of the injector supply banjos while cranking to see if fuel is getting that far. (as an alternative to pulling an injector, not as definitive but far easier)

[RCK974X]

jeff m2 said:

You are going to have to pull an injector.

Pulling the cold start injector could be very misleading because depending on your Texas temp the thermotime switch could say "NO" due to it thinking the engine is hot.

Ah, yes good point - forgot that in a warm climate it may not spray !!

Yep - a main injector is the best way to check.

Although this may sound stupid - are the valves/tappets going up and down ? it's not exactly unknown for the engine to blow its cam drive
gear and mess up the valve timing.... probably not if it's sparking, but just a wild idea.....

[Grady]

jeff m2 said:

You could also crack one of the injector supply banjos while cranking to see if fuel is getting that far. (as an alternative to pulling an injector, not as definitive but far easier)

Jeff - I cracked 3 of the banjo fitting around the top of the metering head and operated the air valve and got 1) fuel from all 3 and 2) a variable amount of fuel (more or less leaking) depending how much I lifted the valve up. Grady

[Grady]

RCK974X said:

Although this may sound stupid - are the valves/tappets going up and down ? it's not exactly unknown for the engine to blow its cam drive
gear and mess up the valve timing.... probably not if it's sparking, but just a wild idea.....

Haven't tried pulling a valve cover off.

I keep thinking there is something simple that I'm missing.
* It went from running to not starting. (no middling issues);
* Nothing was taken apart between the last time it started and the next time it didn't. It just sat for a couple of weeks;
* It cranks until the battery runs down but never shows the slightest sign of catching/firing;
* It didn't die while being driven, something at rest (corrosion, bad switch or relay??);
* It's got spark;
* The black rubber cover of the air valve is new-ish and not cracked, ditto the hose to the intake;
* Everywhere I've tested for fuel its got fuel (banjos on top of the meter and cold start injector);
* The fuel pump is working (but I haven't done a volume test) and holding pressure but I don't smell fuel at the exhaust (but I've had the air hose off) and the plugs don't get flooded.

How sensitive are they to voltage? The battery charges up to 12+ volts but does drop off fairly quickly.

Thanks Grady

[RCK974X]

You probably know the old mechanics rule - "if it's got sparks and fuel it should at least cough now and then...."

It never even coughs.....hmmmm....Plugs are dry.....but fuel pressure at injector feed banjos.....suddenly happened......

The injectors won't open until quite a high psi, they are not like EFi systems. So.....

The only thing I can think of perhaps has fuel pressure but it's too low to operate the injectors ?
This would imply that you have a failed or faulty pressure valve ?
The main pressure valve is in the lump on the side of the metering head, just where the main feed goes in.
Perhaps it's stuck or got crap in it, or seal has failed.....

The warm up regulator adjusts pressure, but only a little bit.. I think you need a proper PSI meter.....

Have a look on the web, there are diagrams, a picture is better then any of our half-assed descriptions !

Sorry - I can't think of anything else....even wild ideas.

[Stog]

I have an old merc that was struggling to start, after much head scratching I cleaned the battery terminals and the difference it made was astonishing!
It wouldn't hurt to give all your electrical connections a quick clean.

[jeff m2]

Grady said:

jeff m2 said:

You could also crack one of the injector supply banjos while cranking to see if fuel is getting that far. (as an alternative to pulling an injector, not as definitive but far easier)

Jeff - I cracked 3 of the banjo fitting around the top of the metering head and operated the air valve and got 1) fuel from all 3 and 2) a variable amount of fuel (more or less leaking) depending how much I lifted the valve up. Grady

This proves you have fuel into the Metering head out to the WUR and back to the head, read Andy's post (RCK74X) as I agree with him.
Time for a pressure test.
For CIS you need a CIS guage, the one with a T, So you can measure system pressure and the control pressure after the WUR.

The fact that you got fuel from the small banjos is encouraging, but is only shows flow! (not pressure sufficient to spray, needs 46 psi)

Edited by jeff m2 on Wednesday 30th September 16:03