I recently purchased a carb overhaul kit for my MTD 608 tractor with a B&S opposed twin engine (all model info below) and also rented a video on carb rebuilding. The video (and everything else I find online) show what appears to be a 4 screw, vacuum actuated, fuel pump with 2 rubber diaphragms, each with 2 semi-circular cut outs that seat up against free floating (not captured) springs.
My problem is that I have what outwardly appears to be the same 4 screw pump, but inside looks totally different - including the springs, which seem to be captured on posts with little "top hat" like retainers, that keep them in place. The carb rebuild kit came with 2 different diagrams, one very thin, the other thicker and with a circular indentation that sitsagainst a single large spring. It did not include replacements for the smaller, captured springs. The kit is 693503.
My engine info is:
bS 17 twin II (IC)
Type 2238 E1
Does anyone know what kind of fuel pump I have? I was given the tractor and don't know its prior service history. It did run, but due to surging appeared to require a carb cleaning.
Since the parts in the kit appear correct for the pump – I’m assuming it’s a newer style 4 screw model. I’m just wondering about the smaller, captured springs that are contained within the pump body. The carb was completely gummed up, so I assume any internal passages on the pump body need to be cleaned as well. I do not want to spray the plastic pump housing down with carb cleaner, but don’t know if there is anything suck inside it. I also am a bit concerned about the smaller springs. The over-haul kit had ever other part (pin for float, jets, seat, etc.) but only the one large spring – not the 2 smallers. I can’t even begin to imagine how one would remove the 2 smallers without destroying the retainers, spings, posts or everything. I’m guessing therefore if replacement was intended the parts would have been provided, but on the other hand – who knows…
Thanks for any input - this was a real curve ball and I can't seem to find much info as everyone seems to know the 3 or 4 screw (typical) models - but this one seems different.