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I've not been putting many miles on my '64 recently since it's getting such horrific mileage (~14 city, last year was ~17). I'm concerned that I'm gassing up my oil... It will also start hard when hot and try to stall at low RPM.
Knowns: CHT is good (have a Hammer). Fuel pressure is good and holds once off (have a FP gauge). O2 is relatively fresh and seems to be working when observed via Hammer.
Power is even, engine runs smooth to redline. It does seem a little down on power, but that's butt dyno and not measured.
Is it time to pull the injectors for cleaning? What else should I be looking at?
Do you have a single belt conversion. Need more info. I had an issue driving driving on the street with the single belt conversion. Didn't want to start when I turned the car off. To sum it off the single belt would not charge the battery right, hindering a proper start up.
What John McM was saying too, how old are your coils?
Also, how old is your batter. The ecu, is pretty sensitive to all this stuff. You'd be surprised.
Almost certain you have a faulty fuel pressure damper. Located directly below the intake in center of the engine bay behind the fan. It is about a $100 part. There is a tiny diaphragm in it that fails over time that allows fuel back into the vacuum and thus hard hot starts, poor fuel economy.
Coils are relatively fresh as well, though they are the dreaded Black Brazilian Bosch units.
Distributor belt is good; both rotors spin as expected.
Stock two (well, three but my AC compressor is in the garage...) belt setup.
Justin said, "Almost certain you have a faulty fuel pressure damper." Pretty sure you're talking about the fuel pressure regulator, which I validated both by removing the vac hose to check for fuel (nope) and also by measuring the fuel pressure under varying conditions. Pump jumpered but engine not running I had about 4 bar, engine running at idle about 3.6 bar, engine at higher rpm about 3.5 bar, engine off for 20+ minutes about 3.8 bar.
I had the car off the road for ~16 months for major maintenance and since then the mileage has been less good than it was before I parked it. I keep track pretty solidly, and it's definitely worse than it used to be. I got 17 in mixed driving pretty regularly, as much as 20 on the highway before the teardown (brakes, steering, oil cooler) but when I got gas yesterday after only city driving for 100 miles it took almost 10 gallons. Not pretty...
Wires were replaced in July '11 at 112k, so 35k miles.
Rotors and caps were done in May '13 at 137k miles, so 10k on those.
Coils (Silver!) in June '13 at 138.5k, so 9k on those.
OXS in Aug '13, 140k so 7k on that.
Plugs (NGK Iridium) in Jan '16; roughly 2k on those.
ETA: I did discover that the idle switch wasn't always closing yesterday and adjusted it for positive function; didn't seem to make much difference as the car stalled pulling into the garage yesterday after a spirited post-adjustment thrash.
Last edited by FeralComprehension; 05-31-2016 at 11:45 PM.
Reason: Moar deets!
The idle microswitch will absolutely have an effect on mpg. Everytime you take your foot off the throttle the switch should close. If you are above 1600rpm, fuel is cut until the revs drop below that threshold. If you're not contacting the switch, no fuel cut, and no fuel savings. The revs can also hang and drop slowly.
For the stalling- sounds like it just needs an idle adaptation.
Feral Justin mentioned the fuel damper-which is the one at the end of the RH? fuel rail. It won't affect
Pressure much at all but it does have a diaphragm that failed lets fuel leak into the intake tract.
All you need to do is pull the vacuum hose and make sure it's dry . Good news is if it has failed it's a
lot easier to replace than the regulator!
@nick- thanks for explaining the FI logic; makes sense, and I never knew it was programmed that way. I can try another adaptation but I've adapted twice recently and my mom always told me not to do that too often Note well that one cannot run an adaption without the idle switch being closed so that ought not to have been an issue.
@prschmn/Justin- I looked for a pulse dampener (have seen them on other cars) but came up scoreless so I checked PET:
@nick- thanks for explaining the FI logic; makes sense, and I never knew it was programmed that way. I can try another adaptation but I've adapted twice recently and my mom always told me not to do that too often Note well that one cannot run an adaption without the idle switch being closed so that ought not to have been an issue.
@prschmn/Justin- I looked for a pulse dampener (have seen them on other cars) but came up scoreless so I checked PET:
OK, thanks- that's the pressure regulator; pretty sure mine is working as intended: no fuel in vac hose, correct pressures under various test conditions.
Also @DobermanDad (sorry I missed answering your question earlier): Battery was new last fall or the year before and if I'm not going to drive it I'll have it on a tender. Also, just now during an adaptation I used the Hammer to check the system voltage; ~13.5V with the engine at idle. I think that system is OK.
05-30-2016, 01:22 PM
Crap mileage, poor hot start/idle...
Note well that one cannot run an adaption without the idle switch being closed so that ought not to have been an issue.
