Fuel pump flow rate (mechanical)

[njoconnor]

Last week I finally got time to install the new fuel pump (mechanical, 1608 72). The car was starting pretty well prior to the swap, now will occasionally fire, then sputter out. Can't use the accelerator pedal with out it killing. This past weekend, I reset the idle speed screw and the idle mixture screw to baseline, per Brad's excellent guide (mixture screw at carb base needed a shot of PB to turn; turns nicely now). I'm about 3 full turns inward on the idle speed screw, and still no change. I can smell some fuel, but not like it's flooded. Figured I'd work backwards and see if the new pump is working.

What's safest way to do that, and what flow rate do I look for? Figure I'll use a rinsed out measuring cup from our garden shed (has metric volume markings). Any other suggestions on the fuel pump or the carb? It's a DHSA2, BTW, and while I'd love to swap in dual IDF's, the exchequer sez "not this year". Also....is there an easier way to get tools onto those two screws????

Thanks.

Neil

[bradartigue]

Easiest thing you can do is remove the fuel inlet line from the carb and stick it in a jar, then crank the engine. It should deliver some fuel. The pump pressure is very low - 3 psi - so don't expect a flood of fuel - you'll get a kind of pulsing flow. Pumps can be installed so that the armature isn't well aligned with the cam on the auxiliary shaft, you may need to remove it and reset it, checking that the arm is not bent and that you can mechanically operate the thing.

I don't understand "3 full turns inward" - you need to seat the screw fully then back it out a few turns. Is that what you mean?

[njoconnor]

Thanks, Brad! I was planning to look at the flow (I appreciate the description, BTW), and if nothing, remove/reinstall the fuel pump....PITA that it is. I don't recall it being as difficult on my 71 Coupe years ago....before a garage, and with only the basic Craftsman 3/8 inch socket set!

"3 full turns in" is the idle speed screw (the one backed out to just touching the lever, then back in in 1/2 turn increments). Idle mixture at the carb base is as recommended: all the way in, then back out 2 full turns. I'll jump on the pump first, then re look at the carb settings; I have your page printed out and taped to the windshield!

Thanks again....

Neil

[fiatfactory]

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[njoconnor]

Thanks for the heads up, Steve. I'll check that if I don't get any (or a dribble) of fuel flow on SAT when I get back in the garage.

Here's hoping I have some luck on this....

Neil

[njoconnor]

Got out to the garage this morning after blowing out the first 4 inches of snow for the season! Using SteveC's suggestion, I removed the fuel pump and carefully reset it so that the pump arm and activating lobe were lined up (nothing bent or broken!). Ran a long fuel line to a glass bottle about 4 feet from the car, cranked it, and fuel was flowing! Reconnected the lines to the carb, cleared the tools, and fired it up.

Started right away, and was idling at about 2500. Fiddled with the idle speed screw, and could not get the idle below 2K. Pushed, prodded, nothing. Shut it down (and noticed one of the leads to the radiator fan switch was loose; fixed that, not expecting it to make a difference...hadn't so far...), then cranked it back up. Still idling at 2K. While futzing, noticed the "fast idle switch" (#20 in your 72 124 wiring diagram and hymnal) was sticky and down. Shot it with some WD40, and it popped out....and the engine shut down!

WDF?

Soooo, back to Brad's instructions, reset the idle speed screw at 1.5 turns past lever contact, and made sure mixture screw was 2 turns out from all the way in. Started it up, and got this nice lumpy 300 rpm idle. Slowly turned in the idle speed screw, got it to stabilize at 900, worked the mixture screw (out about 2 turns, as it happened) until it sounded smooth, and reset idle speed to 900. Gassed it, no stumble, no cough. Shut it off,waited a few, started it again, immediately settled on 900 RPM. AND...during the idle tweaking, I suddenly feel air blowing past my hand. The radiator fan is working!! (Yes, Brad, I stood up and waited until it stopped.... ). One happy rookie in the garage! Not sure how many of these cars have the fast idle switch, but make sure it's all the way up, and moves freely, before trying to work idle and starting issues.

This being finished, I can now move on to the H4 headlamps and relay kit. Also just ordered a 95 amp alternator and mounting block (and, what da hey, a lightweight pulley too...). Once that is done, time for the car's winter nap!

Neil