truck stops on road

[Bambino]

so I'm driving and shift to 4th gear, and it jus dies on me in the middle of the street.. no power , it does it like twice a day, would any one know what could be the problem to this?

[Skib]

start checking connections

 

and give more info

[DAT510]

Power as in electrical?

Or power as in boom boom for the zoom zoom?

:lol:

my 521 likes to kamikaze while driving :lol:

[Phixius]

My 521 Did this, it ended up being one of the switches on the transmission. Since it only did this in that gear i started unplugging shit. Cant remember what one, but I started unplugging sttuff on the trans until it stopped, and it worked. What i found (i think) is tthere is a emissions switch for fourth gear or something along those lines... the way i found out, just idle in the driveway and put it in fourth. Mine just sputtered and died... I think there is jjst two sensors reverse and fourth.

 

Im sure datzunmike (aka tranny god) will know and correct my mistakes...

[MicroMachinery]

It's the 3rd gear switch that you speak of. It's for the 2nd set of points in the dual point distributor(the 2nd set runs at a retarded timing). I dealt with that by unplugging the 2nd set of points... never had a problem since.

 

It was an emissions thing back in the day, where in partial throttle in 3rd and 4th gear, the distributor would run at a more retarded timing, in order to reduce emissions in more residential areas(or so I read). In case you're worried that it will hurt your performance, on the contrary; just set the 1st set of points at the advance that you wish to run at, then unplug the 2nd set. You're in like a dirty shirt.

[Phixius]

Ah yes, now that you mention it, I do believe it was the third gear that would sputter out...

 

Sorry for the misinformation....

 

Edit: actually I cant remember...second, third, fourth... so im no help... nothing new...

[banzai510(hainz)]

just set the 1st set of points at the advance that you wish to run at, then unplug the 2nd set. You're in like a dirty shirt.

 

this will work. But I think 77s went back to single point dizzys

[datzenmike]

so I'm driving and shift to 4th gear, and it jus dies on me in the middle of the street.. no power , it does it like twice a day, would any one know what could be the problem to this?

 

Yeah "no power" means something to you but we're not mind readers, right. Engine or electrical? Describe what happens.

[Bambino]

 

 

Yeah "no power" means something to you but we're not mind readers, right. Engine or electrical? Describe what happens.

okay your driving, you shift to 4th, you press on the gas and it jus starts to die doesn't run

[banzai510(hainz)]

Ok brother.

How about right before it dies you shift to 3rd soes it run again?

 

Im not a 620 expert but if you shift in 3rd and works OK then its a switch I dont know about.

 

How ever on the cheap I would put in a new fuel filter.

 

retime it. as this is cheap.

 

I heard on the later 510s 79 on up when in 5th gear there was something that wen to the carb or soemthing.

 

Dont know if it applies to a 77 620

[datzenmike]

okay your driving, you shift to 4th, you press on the gas and it jus starts to die doesn't run

 

Based on what little you said above, do as Hainz said and change the fuel filter. It does sound like it's starving for gas. A dirty filter is most likely.

[Bambino]

yeah bought one already goin to put it in.. I'm jus going to change everything out.. lol

[datzenmike]

Start with a filter. You may change something in the doesn't work.

[Bambino]

do you guys know if the fuel evap is easy to replace? and a bit confused on where its located

[banzai510(hainz)]

How you figure that is the proplem?

 

open the fuel cap and see if proplem dissapears

[Bambino]

so you mean drive with the fuel cap off??. I took it to get smog and the timing is off and the fuel evap failed so I'm guessing it's turning off on me cuz of the timing is off

[banzai510(hainz)]

OK we need to work on one thing at a time.

 

does this still satll out in 4th while driving.

Replace the fuel filter. less than 4$ part.

If still stalling out try driving it with the cap off(hopefull you got maybe 1/4 tank so gas dont come out)

If works then maybe you need a vented gas cap.

 

Im not a SMOG expert but Im thinking 1977 wouldnt have to go thru smog. So I dont know what intalls a fuel evap system failure. Maybe its just a sniffer saying you gas cap is leaky.(cause maybe its a vented gas cap I dont know)

 

But lets work on one proplem at a time.

 

and you never said it you swap out the fuel filter.

[DanielC]

The Evaporative emission system is pretty much spread out all over a vehicle. The gas tank is sealed, there is some sort of a storage container for gas fumes, and a system of check valves to allow air to enter the gas tank as gas is being used, but not allow air to escape from the gas tank when it gets warm. Additionally, there is a system to purge the gas vapors out of the storage container when the truck is running.

 

Drive the truck until it starts to act up. Stop, and quickly remove the gas cap, as soon as you safely can. If you hear a giant sucking sound as you remove the gas cap, the Evap system is not letting the gas tank draw in air.

 

I do not know if 620 trucks are prone to this problem, but 521 trucks just have a pipe that goes almost to the bottom of the gas tank, without a filter, or anything at the end of the pipe. If there is a lot of crud in the gas tank, it will collect around the pickup pipe in the tank, and stop or slow down the gas flow to the fuel pump. In severe cases, it will stop the fuel flow completely. If you stop the truck, and turn off the engine, the fuel pump quits sucking on the fuel pickup and the crud falls away from the end of the pipe, and the truck will run again.

Sometimes you have to blow air backwards through the fuel line to dislodge the crud.

 

Try doing a fuel pump flow test on the truck. Disconnect the out line from the fuel pump, and put a hose and a suitable container at the end of the hose to catch the gasoline. Start the engine, and at an idle, you should get around a quart of gas a minute out of the fuel pump.

[banzai510(hainz)]

Daniel

Start the engine, and at an idle, you should get around a quart of gas a minute out of the fuel pump.

 

Most L motors dont need a quart a minute to drive in 4th you think?

 

I have seen a cracked hose right before the inlet to fuel pump thus not sucking in enough gas.(sucks more air instead)

 

if Bambibo opens up the fuel filter this will give a indictation of how bad the fuel system gas tank is(rust and sediment)

[DanielC]

OK, you made me dig out my L-16 engine manual.

Fuel pump pressure should be 2.56 to 3.41 PSI

Running at 1000 RPM, the fuel pump should pump 1000 CC in less than a minute.

 

I know that much fuel could make a big block V-8 engine run slobbering rich, but that is what the factory service manual has for fuel pump output capacity.