87blyota

I've got a 87 pickup with a 22r fuel pump was making some noise and I had a spare one so I threw it on well when the old pump was on the bowl and as at the upper range of this sight glass. Now with the new pump its at the lower range truck used to run rich now runs pretty good and idles a crap ton better should the bowl level dropping like that be a concern?

superex87

The purpose of the bowl window is to set the float height. The fuel level should be right in the middle. So no it should not be low.

87blyota

Any reason why changing the pump would change the level?

Odin

I'm not familiar with these carbs but ...

One pump could be supplying more pressure than the other.
Higher float levels tend to create richer idle thru midrange mixtures. As mentioned the float is really designed to run in the middle but some people like to use it for performance tuning if the carb has limited adjustment capabilities.

It's possible one pump simply had too much pressure and was overwhelming a weak needle and seat.

If the needle and seat assembly doesn't hold the extra pressure fuel will spillover and raise the float height beyond where it would normally be and cause mixture problems.

Used to see this on Holley's at the track when I'd try to run 8-9 psi with the Viton 110 needle and seat. For me 7 psi always seemed to be the limit to get a repeatable/standardized float level and a clean idle. The 8 psi everyone always said to run seemed ok for a while but every now and then while in the staging lanes I'd see the float level abnormally high or the idle would act a little rich for no apparent reason. Installing a new needle and seat didn't solve it and either did using a different float bowl.


If the carb has idle mixture screws try adjusting the mixture with a vacuum gauge hooked up to manifold vacuum and the engine at operating temperature. Manual trans in neutral and automatic in drive with the parking brake on. Set the screws so that you get the highest vacuum reading. It should smooth out the idle and off idle transitions a little.
Depending on where you live that may prove to be too rich for emissions testing. They tend to run carbs on the lean side sacrificing smooth idle and power for lower emissions.

87blyota

Thanks for the info. Truck definitely runs alot smoother and isn't as sputtery.

Odin

Has the carb been rebuilt that you know of? If not it might be a good idea to rebuild it.
There are a few threads from several sites with pictures that may help you. There are also a couple video's on youtube.

87blyota

I've been meaning to get around to rebuilding it because it hasn't been done since I've owned it but working 7 days a week and it being my only vehicle makes it hard