groberts615

Everyone, I have a 1965 fuelie and have been running 93 octane with lead added to boost octane. Recently after the transition to summer it has trouble re-starting when hot. When cold it starts right up, no problems whatsoever.

after it gets hot and I stop, the unit has trouble restarting. If I depress the pedal over 1/3 as instructed to activate microswitch it will start for 1 second and then die. If then repeated it will do nothing - just crank. I then need to take my foot off the pedal completely and re-crank and it will cough a little and then just crank. I then can press the pedal over 1/3 again to get it to turn over for 1 second, but still dies.

It will continue doing this and eventually the 1 second start goes to 2 seconds then 3 and then will cough and puke but then start and it takes a little to clear it out but then it is fine again.

Sometimes I just leave it to cool down, then come back in 1-2 hours and it will start up no problem.

Looking on advice on where to start. This unit is correct for 65 and does not have a Cranking Signal Valve, but does have a bypass solenoid. Could the microswitch or solenoid be bad?

Thanks,

wmf62

percolation, NOTHING you can do about it except to learn to live with it...
Bill

rustylugnuts

If you do a search in this forum, you will find a ton of articles relating to this ongoing problem.

This is a recent blog: http://forums.corvetteforum.com/c1-a...t-weather.html

rustylugnuts

Powershift

Good summary.

My personal opinion (FWIW) would be to:

1. Verify that there is no heat riser on the right exhaust manifold, and that you have the correct FI spacer.

2. Use 91-93 octane non-ethanol gas plus Octane Supreme 130 TEL additive to boost the octane rating to about 95 (R+M)/2 or above

3. If above is not sufficient, use a 50/50 blend (or more) of 91-93 octane non-ethanol gas plus 110 octane leaded racing gas or 100LL Av gas.

I am personally doing #3 myself, and find it does make a difference in both hot re-starts and in just typical/normal driving…..especially during the summer.

Not everyone agrees with this approach………..but try it one time and see if it makes a worthwhile difference in your situation/car. If it does, then continue. If not, try something else.



Larry

MikeM

On a 7380 FI unit, hot restart, push the gas pedal ALL THE WAY TO THE FLOOR and crank it until it starts. Shouldn't take but a couple seconds of cranking and when it does start, the engine will probably spit/sputter a little and then clear out.

When you trip the micro switch by opening the throttle (and turning the key to start), that shuts the fuel enrichment passage from engine fuel pump pressure and stops fuel from flowing into the engine so it doesn't flood. Depress the throttle before you start cranking the engine.

You might:

a) not be depressing the throttle far enough to trip the micro switch

b) not be opening the throttle far enough to clear a flooded engine (short story)

c) have a defective solenoid but if it wouldn't shut off after a cold start, it'd continuously flood the engine once it started.

Your hot restart symptoms can be considered normal in some parts of the country.

You can raise the hood when you stop and that will help quite a bit.

groberts615

When you trip the micro switch by opening the throttle (and turning the key to start), that shuts the fuel enrichment passage from engine fuel pump pressure and stops fuel from flowing into the engine so it doesn't flood. Depress the throttle before you start cranking the engine.

Mike,

Would you be able to explain how this circuit works in more detail? You indicated that if it was a bad solenoid that I would have the same flooding problem when it is cold, but I don't step on the pedal at all when the car is cold so the microswitch stays open.

What does the microswitch control, the solenoid under the plenum?

Thanks

MikeM

The solenoid is supposed to pass fuel ONLY when the starter circuit is activated. With your foot OFF THE GAS the solenoid is controlled solely by the starter circuit. When the open the throttle and trip the switch, that overrides the starter circuit.

The starter motor circuit energizes the solenoid and pulls it open to allow gasoline to flow straight to the nozzles with your foot OFF the gas pedal. If you look at the switch, you can see a plastic cam on the linkage that rotates when you open the throttle and that little cam depresses the switch contact and de-energizes the solenoid, closing off fuel flow from the pump.

If the solenoid circuit isn't working one of two things will happen. No cold start or major flooding after the engine starts. I suppose there could be varying degrees of failure in between but I don't know that.

Don't confuse the fuel enrichment solenoid with the add-on siphon breaker solenoid gizmo.

jtranger

A Dewitts radiator for me has been a big help. Runs cooler and cools down quicker after being parked for several minutes. As Mike says, leave the hood up as well. Welcome to the woahs of Fuel injection The good definitely outweighs the bad!

plaidside

This is not an uncommon problem with FI. When I stop my car during warm weather I always open the hood.
This lets the heat escape the engine compartment and helps somewhat during hot starting.
When I start the car after a hot soak I depress the throttle more the 1/2 way and when the car starts I just keep it running until it clears up enough to drive.
Once I start to drive and cooler fuel gets into the spider, all is well.
Joe

rustylugnuts

In relation to fuel injection heat buildup under hood causing hot starting problems, has anyone ever wonder why Corvette designers never made 1958 Corvette louvered hoods functional?

rustylugnuts

1965fuelie

You will need full throttle when starting. Cold engine: throttle to the floor and release, then start engine. Warm engine: throttle to the floor and hold it until engine fires, then release.
My 65 fuelie starts right up every time, but sometimes needs some cranking, 3-5 seconds, when hot.

MikeM

Imagine that? Even in Norway! You guys have E 10 over there?

1965fuelie

Mike, we can still get pure gasolin, but the "normal" fuel is E10, the high octane fuel is (still and who knows for how long) ethanol free.

MikeM

So which one are you using? Straight gasoline or E 10?

rustylugnuts

For those who don't care for ethanol fuel here is a link; http://pure-gas.org/

rustylugnuts

MikeM

I asked in another thread if that made a difference and got only one response. What is pure gas and what is the documented advantage in your neighborhood?

Sometimes we asked silly question to debunk to internet legends.

groberts615

Thanks Mike and Everyone, I have a couple more clarifying questions, please stay with me on trying to figure out operations.

Cold: push petal once to set the choke and then foot off. Microswitch is in a closed state so that when cranking signal voltage is sent the fuel enrichment solenoid opened and fuel goes straight to the nozzles for starting. Check - I do this and it starts right up cold.

Hot: Depress pedal fully (I have been pressing it enough to switch the microswitch, I just checked). This then deactivates the fuel enrichment solenoid so fuel is not directly sent to the nozzles when starting to prevent flooding.

Please confirm that the brass solenoid valve under the plenum is the fuel enrichment solenoid and the anti siphon valve.

If I have a bad solenoid could I be getting direct flow to the nozzles at all times? This would be fine for cold start when it needs high flow, but for hot start it would flood it? Would the car still run if the solenoid was stuck open allowing direct flow? I ask this because It runs rich and pops thru the exhaust on deceleration). Or would the fuel flow be too much and the car would stall out?

Please correct me where incorrect.

Thanks,

MikeM

I think you have it all figured out. Maybe best to check out your hot starts and see if the suggested method will fix your hot start problem.

I guess popping through the exhaust could indicate a rich mixture afterburning in the exhaust but so could a vacuum leak in the exhaust pipes.

1965fuelie

I have always used high octane ethanol free pump gas on my 65 and 67 Corvettes. On my newer cars, a C6 and a Silverado, I fill E10.
I don't know why, but just feel better about ethanol free gas in these older cars.

MikeM

Follow the wire from the switch on the throttle linkage to the solenoid. That is the fuel enrichment solenoid. If someone stuck one of those siphon breaker solenoid gizmos on your FI, it serves a different purpose than a starting aid.