1997 Mercury 175 EFI Loosing Prime After Idle/Low RPM Operation

[Nate L]

Hi All,

I have a '97 175 EFI (Serial # OG584148) that has been running great (and still does when running) however recently has started to loose prime after idling for a while and also if I am running at low RPM and then give it throttle to get up on plane. The primer bulb will be soft but once I pump the primer bulb back to firm it runs great (primer bulb will not be sucked flat but needs to be squeezed again to get it firm). The ball/spring were removed from the anti-siphon valve on the tank previously and I will run off a remote tank next time out just to verify its not something with the fuel line/bulb. Anything else come to mind that could be easily verified/checked? (i.e. pulse pump, VST, fuel pump etc?)

Thanks!

Nate

[JOE54]

replace pulse pump diaphram with oem kit

[turfy49431]

replace pulse pump diaphram with oem kit

Joe is spot on!!!!

[Nate L]

Finally had a chance to install the new oem pulse pump diaphram kit, got the boat on the water and it got up and ran just like it always has (did not stall when throttling up from idle as previously mentioned) however it did cut out again after idling for an extended period, once in gear and again in neutral. Same scenario with regards to re-pumping the primer bulb and it starts right back up again...

Is the next place to look the VST?

Thanks!

Nate

[JOE54]

no ,,,,, is bulb factory merc bulb ????? spin on filter replaced ?????? no air leaks in fuel line !!!!

[Nate L]

Not sure if bulb is merc bulb, but will replace with OEM and fuel line just to eliminate the potential (should the entire line from the tank be replaced or start with bulb to pulse pump?) Also will replace water separator filter. Will report back once complete, thanks for the tips!

Thanks,

Nate

[tim4721]

I am no mechanic, but if it has grey fuel line change it all. The liner in the hose comes apart and will
collapse inside the hose.

[JOE54]

^^^^^^+1 any gray , all oem parts to be used

[Nate L]

Thanks for the heads up on the fuel line, I remember hearing that the old grey had issues. Looking at replacements it looks like OEM is still grey...did they resolve those issues?

[JOE54]

still gray , somewhat better but still see some degraded

[kmelford]

Some OEM fuel lines are grey. The key is to make sure it's the right spec. Here's the BBC link to some info regarding the fuel lines.

http://www.bbcboards.net/showthread.php?t=22490