620 starts to lose power on hills.. thoughts?

[acidjzaz]

So I just got a new to me 620. runs pretty good on flatland ... when I hit freeway hills .. it starts to lose power on me.. could this be a sign of issues with my clutch??

[datsunfish]

A clutch issue will usually be a loss of power to the wheels while the engines revs higher and minimal change in actual speed.If its all dogging out it is more likely an engine,carburetion or ignition issue.

[Z-train]

compression test time:(

[acidjzaz]

thanks .. I 'll have that checked out..

[datzenmike]

The L20B doesn't make enough power to slip the clutch.:D

 

Power loss:

 

Plugged fuel filter.

Float level set too low.

Crushed or kinked exhaust pipe, plugged catalytic converter if applicable.

Bad ignition wires, cap, rotor.

Carb... secondary not opening, plugged secondary jet, stuck power valve.

[fiveNdime]

Check your fuel filter. Our work van did the same thing. crapped out on a hill but was just fine on flatter ground. Dont ask me why this was. but try the filter.

[Bleach]

and if it sputters out on hills only, it could be a bad adjusted float in your carb or a clogged fuel line.

 

I had the issue with the fuel line in a 620. Blew air through it on both sides and it ran great after that.

[Llittle_Llama]

definitely a fuel issue. sounds like it's not able to get enough fuel when the engine is under a load but once on flat ground, there is no load so it can keep up with the consumption...... basically, what everyone else said.....

oh, and if it was the clutch, you would possibly not make it up hills, as it gets worse and worse eventually it will find a hill steep enough to not make it up. if it just slows and the engine bogs or had no change definitely not the clutch, i would be surprised if it was.....

[dat521gatherer]

a fuel issue would make it cut out like its dieing. if your just going slower while your engine is running smmoth without cutting out its probably your vacuum advance or centrifugal weights in your dist. does it sputter or just go slower? air/fuel mixture might be off. lack of fuel will make your engine cut out like it wants to die. other reasons you may go slower is not enough juice like a slipping alt belt. ever drive a car as the alt went out. your lights go dim and car goes slower until it stops. no sputtering though. my .02 good luck

[Z-train]

Fuel consumption is a function of RPM(all other things being equal)If an engine is turning 3000 rpm,it'll use the same amount of fuel,loaded or not.

 

Others here have suggested things like filter,blowing out the line & fuel sock are good ideas.However,a compression test will tell you what shape the motor is in even if leaking rings is not the issue.

[datzenmike]

Fuel consumption is a function of RPM(all other things being equal)If an engine is turning 3000 rpm,it'll use the same amount of fuel,loaded or not.

 

Lets race, you drive up a hill for 30 miles with a 1,000 lb load at 3,000 RPM and I'll do the same on the level ground and see who runs out of gas first.

 

I suggested the filter first because it's cheap and easy to check and to fix. True it might not be that, I think it is, but there are other things to check after that, becoming harder to check, harder to fix and more expensive. Do, and eliminate the simple things first and remember Ocam's razor.

[jesusno2]

your engine may be just flat tired too my z22 in my 720 is pretty tired right now, it will drop speed climbing a incline also.

[Z-train]

Lets race, you drive up a hill for 30 miles with a 1,000 lb load at 3,000 RPM and I'll do the same on the level ground and see who runs out of gas first.

 

 

 

I will run out first because my foot will be to the floor trying to catch you while you are at part throttle.

 

At any given throttle position,"X" amount of fuel is going to flow.Load can NOT change how much fuel gets past the throttle blades at any given position.

 

I agree with the filter possibility.However,this sounds like a compression issue to me AND the fact(as stated in his opening post)that the truck is new to him,doing a simple compression check is in order.

[datzenmike]

I

At any given throttle position,"X" amount of fuel is going to flow.Load can NOT change how much fuel gets past the throttle blades at any given position.

 

Yes, agreed. Throttle position must be constant also.

[Llittle_Llama]

well yeah, but thats where the load comes in.....what your saying is of course it will use more, i gotta use more throttle....duh, thats the load!

[fiveNdime]

I agree do the simple things first. FUEL filter like I said:D

[acidjzaz]

Thanks all, a combination of new wires, water pump, heater core and fuel filter have brought me more power...

 

but as I read through these posts and other posts .. I am realizing that my options for improving performance in a (california) smog legal way .. may be limited... :(:confused:

[datzenmike]

Yup. Get her stock set up and smog legal.

 

Then: Get a KA24 (or whatever) and turbo the 5H!+ out of it and install and have fun until the next smog test. Swap the L20B back in and pass, swap the KA back in... Voila!

 

And if you think that's too hard.... think of the alternative.:D

[acidjzaz]

thats an umm interesting idea datzenmike

 

I just want a little more to tow around motorcycles from time to time...

[DaTsUn72WaG]

Yeah there arent any emissions laws here. woo, my town sucks.