fyton2v
SILVER Star
New to me problem, but I was driving in some new conditions over the weekend. Doing 60 + up a long incline (many miles on a decently slopped grade... 3 or 4%) and my engine did something odd. Going up this pass at highway speeds required a lot of throttle ... a lot of throttle for around 40 minutes. It wasn't floored but the secondary was open pretty much the whole way. Running at a normal operating temp, engine felt smooth and normal. When I was on the throttle, all was fine. But the moment I let off a bit, the engine felt like it would surge for a moment. More throttle... fine. Let off, and an immediate surge just before the engine behaved like it normally would at around 3000ish RPMs without throttle. I don't have a tach so it's kinda hard for me to know what the engine was really doing, but it sorta felt like the RPMs jumped a bit. It lasted for at most a second and I could reproduce it after more uphill and persistent throttle. So I've been searching and thinking about what would cause that and I'm just left with some not very productive guesses.
In normal freeway conditions the truck doesn't do this, even when going up fairly steep grades. But I normally wouldn't be climbing for that many miles.
Anyhow, here are some details:
stock 2F with Aisin carb
Vacuum at idle is pretty steady at about 17.5
No backfiring or pinging (anymore) during normal operation.
Timing is set to 7 degrees before TDC.
Fuel pump and fuel filter are new.
Any guesses? After that momentary surge feeling, it runs as if it never happened, until I let off the throttle again to slow down a bit.
In normal freeway conditions the truck doesn't do this, even when going up fairly steep grades. But I normally wouldn't be climbing for that many miles.
Anyhow, here are some details:
stock 2F with Aisin carb
Vacuum at idle is pretty steady at about 17.5
No backfiring or pinging (anymore) during normal operation.
Timing is set to 7 degrees before TDC.
Fuel pump and fuel filter are new.
Any guesses? After that momentary surge feeling, it runs as if it never happened, until I let off the throttle again to slow down a bit.