Deuce idle issue

[Chinookpilot77]

ok all...I've been trying to figure this one out for over a year...since the day I bought my truck. I have learned to compensate for it, but I'd rather it just be RIGHT!

Ok, my truck starts completely fine...barely touch the button and she's purring like a kitten. She roars going down the road...has plenty of power....in short, she's the best running deuce I've ever driven.


BUT, there is one thing that baffles me. When I am driving down the road...at an RPM above say 2000, and I push in the clutch, the truck has a lot of trouble going from full RPM back to idle...and it will die if not compensated for.

IOT compensate, I just push in the accelerator a little the moment I have it out of gear, and use my foot to give it that little extra bit of fuel it needs in order to return to a 800-1000 rpm idle.

The problem occurs when I need to stop a little sooner than expected and I have to push the brake before the accelerator. I'm a bit worried this could eventually come to a safety issue.

I have installed a new fuel pump, and it runs like a scalded dog...I have replaced all my fuel filters...the only thing I can think of is that it might be a setting, or some adjustment I could make on the IP?

Tell me what you all think. I got my truck back from the paint shop a few weeks ago and I'm anxious to get it on the road and have faith she wont die and embarrass me at every stop light. If you'd like to see pictures of my desert tan bobbed 4-door deuce, please visit the hot rod forum.

Thank you for all your help!

 

[WillWagner]

You installed a new FP...is that the in tank pump, booster pump at the rear of the IP or the whole IP? Did it do this before the replacement? Does it idle when cold?

 

[AceHigh]

Also what RPM do you have it set for at idle? I keep mine up around 750

 

[stumps]

What you are describing is a classic governor problem.

The fuel pedal tells the IP what percentage of full power you want from the engine. It basically changes the spring tension on the governor, and the governor decides how much fuel is necessary given the pedal position, and the current rpm. It adjusts the fuel by spoiling the stroke on the constant stroke IP piston. At idle/low power, the piston stroke is spoiled before hardly any fuel is pumped. At high speed/high power, the IP piston stroke goes nearly the full amount before being spoiled.

Nuff on that.

When the engine is at high speed, and you release the fuel pedal, you are telling the IP to go back to idle fuel/RPM levels. But the engine is already turning way in excess of idle, so the governor completely spoils the IP piston stroke shutting off the fuel. This is exactly the same as what happens when you pull the engine cutoff. Without fuel, the engine drops in speed until it is running below idle speed, at which point the governor turns the fuel back on, speeding the engine up.... It is normal for the governor to hunt a little bit when you drop from high speed to idle, but although the engine speed will rise and fall above idle a bit, the engine should not die.

In your case, the engine is dropping below idle, and the governor is not turning the fuel back on... enough. It is probably simply dirt or gum buggering things up, but it could be a broken governor spring, or a worn out linkage that is causing this problem to happen. It wouldn't surprise me at all to find that your governor isn't protecting your engine from over speed as well.

The simple brute force get-you-on-the-road fix is to replace your IP with a new one. The complicated (more elegant) fix is to clean and rebuild your IP, and re calibrate it to specs.

-Chuck

 

[Chinookpilot77]

I installed a new lift pump...I have done nothing to the IP...and yes, this has been an issue since the day I bought it.

The idle is set for 750, if I bump it up with the hand throttle to 1000rmp, it helps keep this problem from occuring, but doesn't stop it completely.

 

[Chinookpilot77]

oh and yes it idles fine when cold. (but it doesn't get very cold in alabama)

 

[pyrogod117]

I had this exact problem with my last car. It turned out to be something called an idle air control valve that was sticking either wide open or not opening at all right away. It idled fine when cold, but otherwise it did this.

I have no idea if a deuce has anything like this, but I would imagine it has something similar. If not, then I vote on what stumps says with the fuel pump thing.

 

[m-35tom]

stumps is completely right! i would do a couple of simple things first. take the shutoff cover off and pull the control rod to the goveror off. see if the control shaft feels sticky in the rear most position. it should be very free. if it is sticky pull the control shaft that lever is on out being very carefull not to loose the little tab on the inner end. clean everything with carb cleaner or laquer thinner in a spray bottle. spray it up inside the hole where the shaft goes and with a small straight pick tool, reach in and slide the fuel control block up and down gently. very gently. then put it back togeather and run the tank pump while you move the lever. this will flush the cleaner and relube the HH with fuel. if this is all ok and does not fix it the problem is in the govenor section.

tom

 

[Chinookpilot77]

Hmmm...great. Juuuuust Great. Just when I thought my truck was done.

Whats a new IP cost?

Thank you for the information gentlemen. I kinda figured it had something to do with the IP, and I REALLY hope it just needs cleaned up, the engine only has 6000 miles on it for crying out loud!

 

[Chinookpilot77]

Oh Stumps, where would I go to find detailed information about cleaning the IP? Also, any IP rebuild kits out there?

Thanks again for your help.

 

[stumps]

Oh Stumps, where would I go to find detailed information about cleaning the IP? Also, any IP rebuild kits out there?

Thanks again for your help.

Right here in this website. Go to the "Resources" button, and select "Technical Manuals". Scan through the listings until you find TM9-2910-226-34. It will tell you everything you want to know about rebuilding and setting up the IP.

Follow M35 Tom's lead. He has this fix down to a science.

-Chuck