help 79 620 running prob.....

[79datsun620]

i just finished rebuilding my engine after the truck has been sitting for several years and it runs good the first few min. then under moderate accle. it acts like its starved for fuel. from just off idle throught mid rpm's but at full throttle and a little under it runs ok. the problem is intermetent.after i limp it back to the house and let it set for a few min. it will do fine about 1/8 mile and start the symtoms again.any ideas thanks:confused:

[Llittle_Llama]

hows your fuel pump? thats where i would start....

[datzenmike]

Sounds like the secondary opens and it runs good, perhaps the primary jet has some sediment in it. I had an L20B years ago that would do that. When you step into it, the extra fuel flow would draw a piece of debris up and block the jet. Once there it stayed until you shut it off, then it would fall off and away you could go again. Only solution for me was pick a nice day and take the carb off and pull the jet, and there it was, a small speck of ..rubber? Ever since I change my fuel filter with each oil change, saves the hassle.

 

BTW if you re-build get a can of spray carb cleaner with the red straw like the WD-40 cans. I find this works great for flushing out the tiny passages in the carb. Dissolves the crap too.

Edited October 7, 2008 by datzenmike

[Llittle_Llama]

i like his answer better, lol

[]2eDeYe]

I liked yours as well. :)

 

The fuel pump is down by the tank, on the frame. With an old truck that's been sitting there could be derbris all through the system. Start at the carb and work your way back.

 

I had to bybass that damn pump, the clogged filter and the collapsed lines, at a rest stop on Stevens Pass with a borrowed pocket knife. Thankfully, I had a supply of fresh line and had my transfer pump with me. :P

 

Troubleshoot near home ;)

[dat521gatherer]

i dont think it's the fuel pump. it's tour carb or filter.

[79datsun620]

yeah i think datzenmike has it i've changed the fuel pump,same thing. i think ill yank that carb off tommorrow. thanks for the kwik response guys wish me luck:D

[CharlieBucket]

cant wait to see the 620 rolling around cobb county. mine will be on the road soon. been spending to much time on my b210. all i need is a master cylinder and there will be 2 620's out around here

[datzenmike]

I thought the electric fuel pump was only on the factory '77-'79 air con trucks.

[Llittle_Llama]

as far as i know thats why i though check the pump, cause mine had issues like that for awhile till i replaced it.....

[79datsun620]

my 620 has mechanical fuel pump i've never seen one with an electric.i can't wait to get it running either it cost half as much as this gas drinking chevy silverodo to drive.:lol:

[79datsun620]

thanks datzenmike that was exactly what the problem was. got it fixed last night.you da man:D

[]2eDeYe]

Dunno, mine had the electric and a mechanical pump on it...and collapsed lines...with a dash of clogged filters :rolleyes: