1974 75 hp chrysler full throttle surge

[vt750dc]

i fixed the over heating problem, than it stopped charging; so i replaced the voltage regulator. now the charging system works fine again but at 3/4 to full throttle it surges up and down. from idle to 3/4 throttle its fine. all fuel line, filters, pump diaphram were replaced 3 months ago. i think i will disconnect the hot wire on the regulator and try that the next time on the lake just to see what happens, what do you think?

 

[fucawi]

Re: 1974 75 hp chrysler full throttle surge

It must be fuel if its a soft serge ...sharp surge could be igniton ...did you try pumping the primer bulb when it does it ? Dont see how the regulator can affect it as charge system is a very small load on the engine ..( posted the water tell tail stuff on your other post )

 

[jerryjerry05]

Re: 1974 75 hp chrysler full throttle surge

Any in line connectors?They can suck air. Just because it was new doesn't mean it's good.
Tempo squeezies are famous for being bad right out of the box.
Possible tank vent line clogged.
Re-check the fuel pump diaphragm.One backfire can destroy it.
New lines?Even on the carbs?From the pump to the carbs?Ethanol is delaminating older hoses and can cause them to collapse.
First post in the Force section is a post by FrankA called a linc and sinc.Do that.J

 

[vt750dc]

Re: 1974 75 hp chrysler full throttle surge

i did try to pump the primer bulb; but it was still hard' also loosened the bowl screws on the carbs, and they were still full of fuel.
vent on fuel tank is fine also.

 

[mikes 86]

Re: 1974 75 hp chrysler full throttle surge

check needle and seat, mine surged like that, needle was stuck but let enough gas in to run fine at 3/4 throttle

 

[vt750dc]

Re: 1974 75 hp chrysler full throttle surge

new needles and seats; but took apart and made sure they were o.k. they were good and no trash; blew them out with compressed air and re-assembled. re checked all hose clamps. same thing. it does act like a fuel problem; from an idle to full throttle it launches and planes out in 2 to 3 seconds and pulls hard without any problems than 10 so 15 seconds starts to surge up and down; ease out of the throttle and surge slows down somewhat untill a little over half throttle, surge goes away, start to ease back in the throttle surge comes back. just tryin to give all the details i can. i even replaced the vent cap.

 

[devl]

Re: 1974 75 hp chrysler full throttle surge

I have a 1982 Chrysler 105hp thats doing the exact same thing. Did you find a solution yet? If not Ill let you know if I figure it out and please let me know if you do.

 

[vt750dc]

Re: 1974 75 hp chrysler full throttle surge

it rained for a few days so i had some time to tinker. so i pulled the fuel lines and bowls off the carbs and hooked a longer piece of line to the inlet side of each carb to see how much pressure it took to blow through the needle and seats. the top and bottem carb had very little resistance, the center had a flow problem. i pulled the needle and seat out and the rubber seat was almost swelled shut and wasnt letting enough fuel through at a higher rpm. causing it to surge when it ran out of fuel. thanks for all the help.