another water pumping question

[workstoomuch]

We replaced the impeller on my friends 1987 4hp. Johnson due to no water output out of the exhaust or "tell tale" at low speed (trolling rpm). At any speed above idle, water output is good. Impeller housing looks good. I do not see a thermostat or exhaust plate on this engine to check. The water transfer tube to the powerhead appears to be clear. Any thoughts as to what I might check/troubleshoot? Thank you

 

[tvpear12]

Re: another water pumping question

Try a water pump kit, the housing and all, the housing may have wear in it causing your rpms to have to be higher to get any preasure.are you sure you faced all the impellers in the right position?? you seem to be loosing preasure some where. may be the rubber where the tube connects to the housing.