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(Post Link) post #1 of 11 Old 07-05-19 Thread Starter
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won't start

I tried to start the 1975 Alfetta GT today. It has fresh dellortos and 123 ignition, and was running fine until four weeks ago, when I went into hospital. Today I reconnected the battery isolator, pulled the choke on full, gave one press of the throttle and turned the ignition. This previously would start the car every time. Not today. Kept cranking and cranking, tried a few more throttle presses, tired turning the choke off, tried removing the plugs and warming them up with a blow torch, nope. Doesn't want to start.

My current thinking is that the 123 distributor just has too much advance, it only moves off static at 1000rpm, whereas the mechanical one moves off static at 400rpm (crank rpm that is). I guess my next step is to check the spark voltage (have one of those air gap thingies) and then try retarding the spark timing.

Anyone else got any ideas? The battery is on charge as i pretty much drained it trying to start the thing.
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If you ask the AA what the most common cause of "it was working just fine, but now it won't start"? Ran out of fuel.

I always start with the basics. Most engines that have got fuel, air and sparks will start.
  • Has it got fuel?
  • Does the fuel flow to the carbs? (disconnect a hose and see)
  • Is there a spark?
  • Is there air? look out for blocked filters/something sucked into the intake, etc
  • What might have changed since the engine last ran?

Do you get a feeling that the engine is trying to start but can't quite manage it? Or is there no sense of any combustion taking place at all?
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Mine takes a while sometimes after it has sat a little while, I don't use the choke, I just pump the accelerator a few times to get fuel to the carbs, hopefully without flooding it, sometimes it takes a couple of goes, sometimes 5 or 6, but no more than ten,
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(Post Link) post #4 of 11 Old 07-05-19 Thread Starter
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SOLVED! I undid the fuel line at the carburettors; it was dry. I connected my fuel bulb, and kept pumping until fuel was drawn up from the tank into the pump, and filled the chambers, and the pump bulb became rigid. Disconnected charger, connected battery, Choke on, one pump of accelerator, turned key and bingo started right up. So vapour lock I guess. The drive is on a slight incline, and the tank is 3/4 full . Maybe I should park pointing the other way? Or maybe plumb in the fuel bulb permanently.
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(Post Link) post #5 of 11 Old 07-05-19 Thread Starter
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As an academic question, what would be involved to put motronic from a S4 spider into the Alfetta? I'm guessing:
1) fuel tank needs lift pump, plus high pressure pump, similar to 75 TS
2) Motronic ECU, Wiring, AFM
3) Crank sensor and toothed wheel,
4) injectors, and manifold
5) are the heads different? Is there a Varaitor on the s4?
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Originally Posted by alfahaze View Post
As an academic question, what would be involved to put motronic from a S4 spider into the Alfetta? I'm guessing:
1) fuel tank needs lift pump, plus high pressure pump, similar to 75 TS
2) Motronic ECU, Wiring, AFM
3) Crank sensor and toothed wheel,
4) injectors, and manifold
5) are the heads different? Is there a Varaitor on the s4?
That sounds like a great idea! Fit more things to go wrong!
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(Post Link) post #7 of 11 Old 07-05-19 Thread Starter
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Originally Posted by Top Down View Post
That sounds like a great idea! Fit more things to go wrong!
He He. Do you think something is wrong with the fuel delivery system on my car? I can't see any fuel leaks that would cause this behaviour. Maybe my fuel pump is going bad, or there is a check valve near the tank not working?
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do you have an electric or mechanical fuel pump?
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Originally Posted by spiderserie4 View Post
do you have an electric or mechanical fuel pump?
Its a maniacal one. I'm thinking that while the carburettors have pressurised fuel bowls, the outlet valve in the pump is held closed. But when the fuel evaporates out the fuel bowl, such as by the atmospheric port in the air intake, then the output valve in the fuel pump can open. Once this valve is open, the only vlave left in the system is the pump intake valve, so if this is a little leaky, all the fuel will go back to the tank. I figure I can test this by disconnecting the line from the filter to the carburettors, and seeing how long it takes to empty the fuel bowl. This might mean either a glass fuel bowl or some tygon fuel line so I can see what is going on. Has anyone else tested how long it takes a mechanical fuel pump to unprime itself?
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(Post Link) post #10 of 11 Old 15-05-19 Thread Starter
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Today 1 week since the last start I went to replace the fule line into the pump with some transparent tygon hose, and also replace the fuel filter bowl with a glass one (only £12 off eBay for a new one from JJ). Of course I had to prime the pump, which involved a lot of pumping to get the fuel to be seen entering the pump, then more pumping to fill the fuel filter. I did this into a fuel can, and pumped a lot to try and remove bubbles, but they seemed to just want to stay in the line. connected the pump to the carbs, and only needed one pump to top up the fuel bowls in the carbs. Again the car started right up as usual. Now the fuel pump still has the bubble in the feed line, even though the car idled fine right up till the fan kicked in. I will check the feed line every day and see how long it takes to empty. but it is looking like the fuel pump is on the way out. Does this seem reasonable?
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Glad you’ve got it going, that’s positive.

As for the bubble, I wouldn’t worry about that especially if you’ve had it running ok. I’m sure when you’re driving gravity will do it’s thing and it will work it’s way up and out. An alternative way of priming everything is to suck the fuel up through the carb pipe, maybe less chance of an air bubble and it really cleans your teeth!

The pumps are pretty simple and there isn’t much to go wrong. I know people swap them for electric ones but they should be more than up to the job. While you're doing an overhaul I’d strip and inspect in, make sure the push rod is properly seated and replace the gasket.

I’d also replace all the fuel lines, I did this last week as I checked them while the carbs were off to do the steering box and they were cracked. I was very surprised as it’s only a few years since I last replaced them.

I’ve also fitted a one way valve in the line up to the carbs. Mine has never been a good starter and I’d put it down to the fuel in the carbs evaporating and the fuel falling back down the line so I’m hoping the valve with stop this. I haven’t tested it yet though.

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