2002 Yamaha HPDI Fuel Injection Issues
Posted: Thu May 07, 2026 12:15 pm
Figured I'd try to write down some of what I remember from 2 years ago and what I've done recently:
History:
Upgraded the 1990 Evinrude 200HP outboard on my 1986 23' Proline Offshore with a good-used 2002 Yamaha HPDI 2-stroke 200 HP outboard, I think in about 2019, it had about 950 hours or so on it. Changed primary hull-mounted spin-on filter to a "fine" yamaha-recommended - can't remember if it was 5 micron or 2 micron, but whatever Yamaha recommended. Reading about high-hour (>1000 hour) HPDIs, I can purchased spare medium-pressure filters and a set of "mystery" filters that are last-chance screens in the injectors, but never installed because it ran fine.
Used it for several years without issue and it ran great.
2022 I had a fuel tank leak on the boat, had to cut the floor out and get a new custom aluminum tank fabricated. Installed and I thought all was good.
2023 and 2024 I rented a marina slip to keep the boat at for the summer. Due to low-in-water deck scuppers (likely a combo of water-logged boat plywood and heavier-than-design later-model outboard) the scuppers took on water periodically. Additionally, unknown to me, I had not correctly assessed the 1.5" fill-hose condition during my tank install. The fill hose had rotted away between the deck fitting and the tank, and every time I put gas in the boat I was pouring gas into the bilge. I didn't realize this until the third chemical-related failure of the bilge switch.
Based on bilge pump switch failure and low scupper height, the boat partially-flooded at the dock and was about 18" full of seawater. Because of the fill hose issue, the fuel tank took on seawater. I was able to get the boat from the marina to the boat ramp, but as I got the boat on the trailer the engine stalled, likely due to salt water pickup from the tank. I got the boat home from that adventure, and based on possible fuel system damage, I immediately used a regular gas-can to pull clean fuel from and cycled the engine including dumping the on-engine vapor separator tank repeatedly until it ran successfully and well to try to avoid fuel system damage. I also removed the fuel tank again, found the hose issue, replaced the fuel fill and vent hoses and vent. Re-fiberglassed in the deck required from tank removal, and thought I had it cleaned up. When attempting to restart the engine, I determined the electric medium-pressure pump was bad (clearly corroded from seawater exposure), so I replaced that. I also replaced both crank-case windage driven vacuum lift pumps since they weren't expensive and I had tried to rebuild the old ones but the housings were a little corroded.
Since then it never seemed to really run right. I believed I had bought a too-cheap medium-pressure electric pump, so I bought a better one and installed it, but after that I could not get even decent on-trailer/water-ear-muff operation. Would not rev up and sporadic idle stalling.
I have now removed the high pressure fuel headers and replaced all last-chance screens on the injectors. All looked fine. I removed the high pressure pump and disassembled/cleaned everything I could find with no real findings. After reassembling and seeing no improvement, I pulled a couple more high pressure pump access covers that I had not looked in. There were two check balls to prevent fuel backflow. I dropped one back into the high pressure pump, and had to remove the pump again to find the ball. Once removing the pump the second time to find the ball bearing, I discovered there were two more "last-chance"/mystery filter screens in the high pressure pump. I believe one of them was scummed over pretty badly. It ran much better after changing, but I've only driveway/ear-muff run it so far.
I want to test drive and see how it goes before I keep tearing my hair out.
Brief system overview:
Fuel tank -> spin-on filter -> basic engine inlet paper filter -> windage lift pumps (2X in parallel) -> vapor separation tank / intermediate (~50psi filter) -> medium pressure filter (canister) -> high pressure pump (includes 2 last-chance/mystery screens) -> injectors (each w/ last-chance screens)
History:
Upgraded the 1990 Evinrude 200HP outboard on my 1986 23' Proline Offshore with a good-used 2002 Yamaha HPDI 2-stroke 200 HP outboard, I think in about 2019, it had about 950 hours or so on it. Changed primary hull-mounted spin-on filter to a "fine" yamaha-recommended - can't remember if it was 5 micron or 2 micron, but whatever Yamaha recommended. Reading about high-hour (>1000 hour) HPDIs, I can purchased spare medium-pressure filters and a set of "mystery" filters that are last-chance screens in the injectors, but never installed because it ran fine.
Used it for several years without issue and it ran great.
2022 I had a fuel tank leak on the boat, had to cut the floor out and get a new custom aluminum tank fabricated. Installed and I thought all was good.
2023 and 2024 I rented a marina slip to keep the boat at for the summer. Due to low-in-water deck scuppers (likely a combo of water-logged boat plywood and heavier-than-design later-model outboard) the scuppers took on water periodically. Additionally, unknown to me, I had not correctly assessed the 1.5" fill-hose condition during my tank install. The fill hose had rotted away between the deck fitting and the tank, and every time I put gas in the boat I was pouring gas into the bilge. I didn't realize this until the third chemical-related failure of the bilge switch.
Based on bilge pump switch failure and low scupper height, the boat partially-flooded at the dock and was about 18" full of seawater. Because of the fill hose issue, the fuel tank took on seawater. I was able to get the boat from the marina to the boat ramp, but as I got the boat on the trailer the engine stalled, likely due to salt water pickup from the tank. I got the boat home from that adventure, and based on possible fuel system damage, I immediately used a regular gas-can to pull clean fuel from and cycled the engine including dumping the on-engine vapor separator tank repeatedly until it ran successfully and well to try to avoid fuel system damage. I also removed the fuel tank again, found the hose issue, replaced the fuel fill and vent hoses and vent. Re-fiberglassed in the deck required from tank removal, and thought I had it cleaned up. When attempting to restart the engine, I determined the electric medium-pressure pump was bad (clearly corroded from seawater exposure), so I replaced that. I also replaced both crank-case windage driven vacuum lift pumps since they weren't expensive and I had tried to rebuild the old ones but the housings were a little corroded.
Since then it never seemed to really run right. I believed I had bought a too-cheap medium-pressure electric pump, so I bought a better one and installed it, but after that I could not get even decent on-trailer/water-ear-muff operation. Would not rev up and sporadic idle stalling.
I have now removed the high pressure fuel headers and replaced all last-chance screens on the injectors. All looked fine. I removed the high pressure pump and disassembled/cleaned everything I could find with no real findings. After reassembling and seeing no improvement, I pulled a couple more high pressure pump access covers that I had not looked in. There were two check balls to prevent fuel backflow. I dropped one back into the high pressure pump, and had to remove the pump again to find the ball. Once removing the pump the second time to find the ball bearing, I discovered there were two more "last-chance"/mystery filter screens in the high pressure pump. I believe one of them was scummed over pretty badly. It ran much better after changing, but I've only driveway/ear-muff run it so far.
I want to test drive and see how it goes before I keep tearing my hair out.
Brief system overview:
Fuel tank -> spin-on filter -> basic engine inlet paper filter -> windage lift pumps (2X in parallel) -> vapor separation tank / intermediate (~50psi filter) -> medium pressure filter (canister) -> high pressure pump (includes 2 last-chance/mystery screens) -> injectors (each w/ last-chance screens)