Starting Problems, Starting with Throttle but Won't Idle Options

[Superhawk996]

Impressive....as they say "a picture is worth a thousand words" and thanks for going to all the trouble to set this up. It definitely shows the appropriate 2.7-amp draw. It's more and more pointing to an internal failure of the fuel pump overheating. Is this a correct assessment in your opinion? I will forward these pics to the mechanic.

Yes I agree that your pump is failing due to the high current draw.

I don’t think it’s the source of your difficult hot start issues since you have 34-35 psi being produced by the pump. The symptoms your mechanic describes about the addition of the 250 ohm resistor and how it helps cold start but hurts hot start aligns to a CHT problem.

I agree that I would replace the pump and fix any damaged wiring but wouldn’t let that derail the efforts to solve the hot start and getting a new CHT into it.

While you’re doing the pump - I’d change it to a two port pump and relocate to the front. But again, this is a whole different diversion and won’t affect your immediate problem of difficulty hot starting.

[wonkipop]

i pretty much agree with @Superhawk996 .

the cold start then hot start problem is highly likely down to the CHT.

the fuel pump issue is separate and the mechanic has spotted it.
now it may well be that the problematic fuel pump was the cause of the initial problem which emerged suddenly while you were driving and the car lost power etc.
could well be it had been developing for a while and getting worse but you did not notice. nothing to notice as it was still making pressure. but drawing excess current.
could be the dual relay got so hot it started being erratic shut down the fuel pump.

its not clear to me whether the CHT got replaced along the way in these repairs with previous mechanics and was wrong or there was a wrong CHT all along. seems to me it must have been replaced?

whatever. the mechanic seems to have gotten down to the two issues.
which are overlapping it is highly likely.

i am not a big fan of moving the fuel pump. esp if the plastic fuel lines through the tunnel have not been replaced with steel lines. i would not pressurize those plastic lines to 35 psi if they are now half a century old. changing to a front fuel pump location should only be done with replacement of the lines in the tunnel. it will run just fine with a turbine pump in near stock location.
i say near stock as its a difficult fit to put one in where the original is located on a 74.
it might have to be mounted to the rear passenger firewall bulkhead on the engine side near where the original was. the reason for that will be trying to get a supply or a delivery line out of it without excessive curvature. i know that from recommissioning mine. the pump should work fine in near stock location. to guard against vapor lock reflective shielding of the fuel lines across the back bulkhead and fuel pump works very well.

however as long as the tunnel fuel lines are being replaced nothing wrong with front relocation. with the proviso that its wired in correctly to preserve the L jet dual relay control of the fuel pump. ie when engine stops running fuel pump stops running.
its a great safety feature, which i understand the D jets lack.

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[Superhawk996]

Good point on the fuel lines - sometimes I assume people would have replaced by now.

[wonkipop]

Good point on the fuel lines - sometimes I assume people would have replaced by now.

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there are still a lot of ticking time bombs out there mate. (IMG:style_emoticons/default/smile.gif)

mine was one until 6 years ago. good thing i was not driving it for the 16 years before that. (IMG:style_emoticons/default/sad.gif)

what i found when i pulled them out was generally where they ran in the tunnel was they were micky schmidt as we say down here. perfect condition. untarnished by UV, heat or time. but about 2 inches or so from the end of the tunnel to the rear firewall and then along the rear firewall they were one and a half foot in the grave.
the bit that was inside the end of the tunnel was the worry. you could imagine that failing. probably still ok with feeble pressure (ie none, just weak suction flow) but i would not have liked to have shifted the pump and given them 35 psi.
i ended up making my own steel lines and replacing the lot. i've left the pump in stock position but its shielded with reflective foil. so far no issues with vapor lock.
but to be truthful i only ever suffered from a couple of incidents of that way back in time anyway.

[wonkipop]

double post for some reason, deleted,