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2003 RX DI Instant Drop in Fuel Pressure

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RideRed0331

RideRed0331

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I have a 2003 Sea Doo RX DI with 130 hours on it, bought not running and sitting for about a year. I pumped out the old fuel, replaced with fresh 93. I also hooked up a fuel pressure gauge, and when connecting my lanyard I am getting 17psi, which nearly instantly drops back down to zero. New battery, fully charged and still on the trickle charger.

I already replaced the fuel filters, and the entire pump with the HFP-500DI-X (it came with the ski) and am getting the exact same results as with the OEM pump. The manual states to check the fuel rail for leaks (I am not visibly seeing any leaks). It also states to check the fuel pressure check valve, but I am not able to locate this. Also, do these skis have an external pressure regulator? If so how can I test it?

Thanks in advance
 
The fuel pressure regulator is on the fuel rail, under the black cap, between the fuel injectors. The air pressure regulator is right next to it and looks similar. Either your fuel pump is not putting out the correct pressure or your fuel pressure regulator is bad. You should see 27 psi when you insert the key and then 107 when cranking/running. The OEM pump has an internal check valve - do not believe aftermarket ones do so it will leak down when the pump stops. This is not a big problem but will result in longer cranking. But only seeing 17 with the pump running is a problem.

You can buy a brass needle valve at Home Depot and put it on the pump outlet to make sure the pump will build pressure. Squeeze down on it (do not shut off completely) and the pressure should rise to at least 107 psi. If you can't hit that number, the pump is not going to work.
 
The OEM pump was doing the exact same thing, which is why I replaced it with the HFP-500DI-X. The results between both pumps are 100% identical when I installed the lanyard, they hit 17psi and drop back to zero.

Do you have any pictures of the needle valve I should get to try the pressure test with? I am essentially just restricting the hose enough to raise the PSI to 107 if I’m following? Basically putting my thumb over the end of a garden hose in a sense?
 
Yes I believe so, I saw the red rubber washer on the bottom when I put the lowest filter on before I reinstalled the assembly
 
Yes to "thumb over the hose" but you need to keep some fluid moving at all times. This is what I bought to make it work:
https://www.homedepot.com/p/Everbilt-1-4-in-x-2-in-MIP-Brass-Nipple-Fitting-802259/207176694https://www.homedepot.com/p/Everbil...13482669;205448635;205448634;-_-300096254-_-Nhttps://www.homedepot.com/p/Everbilt-1-4-in-FIP-Brass-Tee-Fitting-801969/300096762
And I put a 1/4 pressure gauge on the tee. The threaded nipple fitting fit into the fuel hose and secured with a hose clamp. Route the outlet of the needle valve to a cup/bucket during the test.
 
Ok I thought I had it, but now I’m not following based on the materials you used for your test. I have my fuel pressure gauge in place of the in-line filter coming from the tank on the feed line. If I add the needle valve in-line right after the gauge, it leaves me with essentially the same results, no?
 
Yeah, put the need valve after your gauge. I was sharing how I did it from scratch. Not sure what you have to work with, but you want the needle valve last and dumping to a cup/bowl/etc.
 
Just an update, the pump is now reaching 100psi after about 2 seconds of cranking and the ski fires up. It also hits 27/28psi when I click the lanyard on. However, it then dies and fuel pressure drops again. It’s almost like the power to the pump is cut and the ski dies right back out. I do not believe my issue is pump related as the one in the ski is now brand new.

What should my next course of action be?
 
I would attach a volt meter to the battery start the ski and watch the volt meter when the fuel pressure drops. If the voltage drops during the spike then you know the aftermarket pump is pulling too much voltage. Aftermarket pumps are notorious for pulling too much voltage. JMTC
 
How can I check the regulator? I’ve searched and searched. Even if I google search “RX DI Fuel Pressure Regulator” it does nothing for me. It gives me results to motorcycle replacements, nothing for my ski
 
The fact that you get 27 with the key means the regulator is at least somewhat functional. I had my regulator out a couple days ago - not too difficult and I think I saw a used replacement on e-bay. No idea how you would test it, but I suspect your issue is elsewhere.
 
WaarrEagle said:
The fact that you get 27 with the key means the regulator is at least somewhat functional. I had my regulator out a couple days ago - not too difficult and I think I saw a used replacement on e-bay. No idea how you would test it, but I suspect your issue is elsewhere.
Click to expand...
I think his problem is in the fuel tank most likely that slide seal they use in there
 
Tyman2020 said:
I think his problem is in the fuel tank most likely that slide seal they use in there
Click to expand...
Could be, or still a bad pump. My pump was displaying similar performance of 80-100 during cranking/idle but only put out 60 when I put a needle valve on the outlet. I wonder if the same is happening here. Putting a needle valve on the pump outlet and finding a way to supply constant air pressure to the fuel rail are 2 tests that would tell you for sure where the problem is.
 
Is there a gauge set up I can purchase for the DI? I'd like to be able to monitor pressures while the ski is running. I have 2 more DIs I'll be replacing engines in and I'd like to test the fuel systems thoroughly.
 
etemplet said:
Is there a gauge set up I can purchase for the DI? I'd like to be able to monitor pressures while the ski is running. I have 2 more DIs I'll be replacing engines in and I'd like to test the fuel systems thoroughly.
Click to expand...
I bought this kit from Amazon and found it really useful: https://www.amazon.com/gp/product/B00VV29NHM/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

It comes with a tee that fits perfectly in the hose lines around the in-line fuel filter and has a nice long hose to the gauge that lets you route it to under the storage compartment for easy viewing when riding. I also used the tee to splice inline to the air hose from the air compressor to the fuel rail for troublshooting. Probably the best $35 I spent on my DI thus far!
 
I am also thinking my issue may be with the sliding seal at this point. I created a new topic hoping someone can point me in a direction to bypass the sliding seal style spring loaded pump housing

WaarrEagle said:
Could be, or still a bad pump. My pump was displaying similar performance of 80-100 during cranking/idle but only put out 60 when I put a needle valve on the outlet. I wonder if the same is happening here. Putting a needle valve on the pump outlet and finding a way to supply constant air pressure to the fuel rail are 2 tests that would tell you for sure where the problem is.
Click to expand...

How can I test my air compressor to verify I am getting constant pressure? I do not want to cut that factory braided hose to Tee into it? Then at least I could eliminate that from possibly being my issue
 
just get some 5/16th id submersible fuel line get a foot..I used a old style wire hanger the thicker ones and hose clamps to hold the pump to the bottom of the tank. Do yourself a favor and get a foot of cheaper hose to mock up and get the length correct that submersible line isnt cheap
 
I was unable to find a way to clamp onto the existing high pressure air hose, hence why I cut in. A replacement is only $40 on e-Bay. In hindsight it was a great decision because I was able to 1) verify output of the air compressor and 2) use it to inject air into the fuel rail to ensure correct operation of the air pressure regulator and 3) inject steady pressure while troubleshooting the fuel pump.
 
I have a complete spare system I can play around with... all the hoses too. I just want to be able to plug in right at the fuel rail or close without any further disassembly. I might have to get busy on this as I have a 3 DI's and a fella that needs a hand with his. LOL
 
I may have discovered my issue, let me try to do my best to explain this.

So pictured is the top hat to the fuel pump assembly. The plastic spigot on the underside slides into the rubber sliding seal on the aluminum standoff into the actual fuel pump. Now, if I hold my finger over both the brass feed and return nipples on top of the housing (that run to the DI rail), and blow into the black plastic spigot, it holds zero pressure. Air blows back at me. I tested it with soapy water and it bubbles like crazy on the underside. Now unless I’m looking at this wrong, I believe I should be able to blow as hard as I possibly can into that spigot with no air leaking, correct? It is clearly rusted, and I resealed it with silicone as best I could, but air still escapes out the bottom where the return nipple drains fuel back into the tank. image.jpg
 
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