1987 Mariner 70, 4 cyl SN A145589 on Starcraft FM160

by Patrick
(Yuma AZ)

1987 Mariner 70,

for the past few weeks I have experienced an issue with acceleration. Occasionally when advancing the throttle it will catch and normally run to wot. Most of the time though it will hesitate around 2800 rpm and start to stall. If I juggle the throttle sometimes it will catch and run up to wot but more frequently it dies or tries to. I have rebuild both carbs, replaced the fuel pump (with an amazon pump), pulled and checked plugs, checked compression although I can't remember what they were, I felt at the time they were likely sufficient. Ive pulled the pickup tube out of the tank, cleaned screens and verified it pulls from the tank. Just this past week I noticed at different times the following: one time while it was bogging around 3000 i pushed the key in and each time i did it would accelerate like it was fuel starved...the next day it did nothing. Another time while it was bogging I reached over to squeeze the bulb and it was soft, then hard then soft. When it catches it will routine accelerate to around 4600 ( I haven"t tried to push it beyond and seems to run well while at wot. Idle has become a bit rougher over the past 3 months. Starting varies from instantaneous to grind grind grind.

Availability of techs in the yuma area is thin so I'm kinda on my own.