'74 2L Starts Then Dies, Never a convenient time... Options

[GregAmy]

Nice beautiful New England Day, heading off to the Manchester CT car show and...car won't start. Cranks, a few cylinders fire, then it dies. I cycle the key and hear the pump running and then stop (as before) and same thing: spits then dies.

I tried cycling the key a few times, with the mindset of building more pressure, and it spits a few more cylinders then dies. Even got it to rev a little bit with a half-dozen key cycles, but always dies.

Only other symptoms is that I noticed the last time I drove it earlier in the week it was dying when I put in the clutch. Was not consistent, only did ti a few times, but that was unusual behavior.

Stock 2L fuel injection, but with cold start and idle air bypass systems disabled; been running fine like this for the several years I've had it.

Checked all the relays, each works with the heater blower. Swapping them makes no difference (which I expected, given the pump cycles with the key). My guess is that however the pump is supposed to continue to run after releasing the key, it's not getting the power it needs (just a guess, I've not gotten under there with a voltmeter to verify). The wiring diagrams are not clear (to me) how that power is applied to the fuel pump relay.

Any way to quickly salvage my afternoon trip to the car show, or am I using my beautiful afternoon to swap the street car onto the lift for extended diagnosis?

40-yr-old electrics, gotta love 'em.

- GA

[GregAmy]

And the answer is...(or seems to be...)


Wait for it...


Bad MPS.

Haven't taken it for a drive yet (April showers and all that) but Tangetine rebuilt the MPS and it has totally transformed the car. Starts, runs and idles, doesn't suddenly die, idle is consistent.

Ed noticed a lot of my symptoms, plus some others I offered (such as I gave the ecu dialed full rich to stop surging at idle, and poor throttle response on the road) and figured I was running lean, and that the MPS needed rebuild. I found that diagnosis odd, given the MPS held a vacuum. So Chris suggested I try adjusting it instead. I removed it and handed it to them to mod for that, and they found a cracked diaphragm. They rebuilt it and when I bolted it on the car and started it up the difference was immediately evident.

Adjusted the MPS richer to move the ecu knob to the middle, adjusted ignition timing to 27, set idle and now it starts nicely. Plus, running lean and 10 degrees too much timing could also explain why it runs too hot in the summer.

As noted, I still need to take it out on a nice day, but I think we have this licked.

Scroll up and see if you called it like Ed did. (IMG:style_emoticons/default/wink.gif)

[DRPHIL914]

And the answer is...(or seems to be...)


Wait for it...


Bad MPS.

Haven't taken it for a drive yet (April showers and all that) but Tangetine rebuilt the MPS and it has totally transformed the car. Starts, runs and idles, doesn't suddenly die, idle is consistent.

Ed noticed a lot of my symptoms, plus some others I offered (such as I gave the ecu dialed full rich to stop surging at idle, and poor throttle response on the road) and figured I was running lean, and that the MPS needed rebuild. I found that diagnosis odd, given the MPS held a vacuum. So Chris suggested I try adjusting it instead. I removed it and handed it to them to mod for that, and they found a cracked diaphragm. They rebuilt it and when I bolted it on the car and started it up the difference was immediately evident.

Adjusted the MPS richer to move the ecu knob to the middle, adjusted ignition timing to 27, set idle and now it starts nicely. Plus, running lean and 10 degrees too much timing could also explain why it runs too hot in the summer.

As noted, I still need to take it out on a nice day, but I think we have this licked.

Scroll up and see if you called it like Ed did. (IMG:style_emoticons/default/wink.gif)

I did!!!! Post #13 on first page! As I said then, had the same symptoms and frustrated the hell out of me. Almost sold the car-
Congratulations hope you can now enjoy driving it!! Maybe it will make it to Okteenrfest this year!!

[GregAmy]

I did!!!! Post #13 on first page! As I said then, had the same symptoms and frustrated the hell out of me. Almost sold the car-

(IMG:style_emoticons/default/drunk.gif)

Just a quick follow up...the car is totally transformed. For those of you that have never experienced a bad MPS, trust me, this is like an automotive religious experience. Just spend the money because now my car that ran like total hell is a joy to drive: starts, idles, runs smooth, warms up nicely, and doesn't die when I push in the clutch at a light...with this system running correctly all thoughts of carbs is long, long gone.