1998 225 opti lack of fuel

[ncshooter]

Og743300 225 opti. Started engine on muffs today and it idled perfect for 10 mins. Suddenly stuttered and shut down like it ran out of fuel. I checked the fuel side rail and the rail was empty. No pressure at all in fuel rail when key is cycled. Pulled hose off the top of the hpfp and got nothing but some bubbling from it during key cycle. Checked low pressure pump and confirmed its filling the vst. Vst drain at lower front of vst has fuel. Just wanting to confirm that I'm looking at a hpfp issue??? Was going through my spring service routine and replaced fuel lines and primer bubble. Bubble gets firm. Also I'm hearing squirting inside the vst a few seconds after key cycle. Going to disassemble vst tomorrow to check needle valve and float. If the drain on the hpfp side of vst has fuel and the hp pump isn't pumping is it just stopped pumping? I'm assuming the hp pump is getting fuel to pump since vst is full but I could be wrong. Any tips would be appreciated. Already ordered a new hpfp to replace since I'm sure this is the factory hpfp from 1998

[lpugh]

Check the boot that seals the high pressure pump to cover

[ncshooter]

Will do. Does anyone have a part number for the seals I need so I can just replace them while I'm inside the vst? The hpfp I ordered didn't come with anything except the pump

[EuropeanAM]

Best method to look up and/or order parts is in the Parts Catalog, using your engines serial number. Try: mercurypartsonline.net

You can also see the latest part number/pricing as items are placed in the shopping cart.

[ncshooter]

Update for anyone who may find this thread in the future. Removed fuel filter and found that the filter itself was under pressure from priming bulb. Immediately removed vst and disassembled. Everything looks clean and I didn't notice anything but I went ahead and pulled needle and float and clean all passages with carb cleaner. Then I made up some jumpers and put 12v to the hpfp. It spun up fine. Reversed polarity to hpfp to spin it backwards. Cleaned screen on bottom of pump also. Reassembled and Immediately noticed a stronger sounding pump. Engine fired up and has ran great on the muffs since. I'm thinking that the passage from the filter to the "bowl" of vst was clogged. Needle seemed clear but apparently something was inside it. Will test on the water tomorrow and give final verdict here to finish thread. Thanks for all who responded

[ncshooter]

Best method to look up and/or order parts is in the Parts Catalog, using your engines serial number. Try: mercurypartsonline.net

You can also see the latest part number/pricing as items are placed in the shopping cart.

Thank you Don! I appreciate the response

[EuropeanAM]

Another note: Keep in mind that if the transfer passage is plugged/restricted, OR the low pressure pump is not functioning, you'll have no output from the HP pump when it runs.

[ncshooter]

Another note: Keep in mind that if the transfer passage is plugged/restricted, OR the low pressure pump is not functioning, you'll have no output from the HP pump when it runs.

10/4. Low pressure pump is running good. I'm assuming the passage from filter to "bowl" in vst was clogged causing the hpfp to not have access to any fuel to pump. Now that fuel is flowing to the hpfp its pumping good and strong. I'm gonna blame this on 2 things. Ethanol fuel and not starting the engine since last summer..lol. will post final results after on the water test tomorrow after church

[ncshooter]

Well well well....went out today and for about 15 mins motor ran great. Then slowly started sputtering little by little till it cut off to never start up again. Took it back home and removed vst again to check thing. Still found lots of pressure on the fuel filter when I removed it. As I'm unscrewing the filter lots of spurts of gas. Cleaned needle and seat again and re installed vst. After purging some air from system engine fired up and idled perfectly again. Went to Rev it up and got a sudden sputter and a cloud of blue smoke then it cleared up and idled great for 20 mins. Cut it off and went inside. Went back out 2 hrs later and it's back to barely running and sputtering like crazy. New hpfp will be here tomorrow and so will a new fuel pressure gauge. Hopefully I can find this demon soon

[ncshooter]

As much as I would love to just drop it by a shop I can't justify spending 1000$ on this thing being a 98 when I can buy a slightly newer 2smoke opti for 5 or 6k. Thoughts???

[ncshooter]

20240311_082313.jpg

[smoken86]

Well it seems like you already know what the problem is. If cleaning it makes it run for a while I would clean it again and probably replace the needle maybe even the float. I would also change the filter and inspect the lines from the pulse pump.

On a side note is the float is properly set?

[ncshooter]

20240311_082302.jpg
Diapghram tear causing issues. Replaced with a new purple one and it's running smoothly again. Checking fuel pressure showed me I had none which lead me to fuel pressure Diapghram. I guess it's always good to check these first when having opti issued. Thank for all replys.

[ncshooter]

Well it seems like you already know what the problem is. If cleaning it makes it run for a while I would clean it again and probably replace the needle maybe even the float. I would also change the filter and inspect the lines from the pulse pump.

On a side note is the float is properly set?

I tried to post both pics in one post but I'm still learning how to post pics here..lol. that's my issue is pics above

[smoken86]

So is that the fuel pressure or tracker valve? While it is certainly bad it wouldn't cause the VST not to fill. It would make it run pig rich and stall.

[ncshooter]

So is that the fuel pressure or tracker valve? While it is certainly bad it wouldn't cause the VST not to fill. It would make it run pig rich and stall.

It's the fuel regulater valve. I don't know how it ran at all. It would idle ok for a min then go crazy. Fuel pressure was all over the place. I have no clue how it ran as much as it did. I was chasing ghosts messing with the vst I guess.

[lpugh]

Did you use the special tool required to press the cover down and keep it aligned? If not, you will probably be replacing it again soon.
20240311_111257.jpg

[ncshooter]

I made a tool like that 2 years ago when diagnosing another issue. Although I will say that my personal fuel regulater can be pushed flat with hand pressure. The tool does help but it's possible to do without it if your careful.

[EuropeanAM]

Possible- yes. I won't, though (I use it on both the Air and Fuel as alignment can make the difference between pinching a diaphragm or not pinching a diaphragm).

[ncshooter]

Possible- yes. I won't, though (I use it on both the Air and Fuel as alignment can make the difference between pinching a diaphragm or not pinching a diaphragm).

Your right it's safer to use it. I made one from a piece of flat bar stock aluminum and 2 long bolts with the same thread. I used a tiny dab of grease to hold diapghram in place while I place the housing. Keeping it straight while you compress the spring is what gets ya. Anyways I appreciate the reply.