Hpdi Issue

[SKEETERMAN]

After dewinterizing the boat in April the motor ran great for the first two outings (about 4 hours) I decided to change the plugs and when i did it runs fine in the higher rpm's but stalled at idol when shifting into neutral or reverse. I figured i got a bad plug as i know the model # was correct. Luckily i saved three of the old plugs and swapped out the starboard side first with no luck and then the port side. Motor ran a little better with the older plugs in the port so i ran out and got three more plugs for the port side and installed them. My issue has gotten better but instead of the engine stalling 50% of the time it now stalls 10% of the time. This motor ran perfect before i changed the plugs and i dont think it has ever stalled once since i have owned it. The odds of getting bad plugs from the store twice is slim to none odds. Any suggestions??

[glen e]

double dose it with ringfree....

[SKEETERMAN]

I am pretty good about useing ring free and startron most of the time. Being that I use ring free a lot at the regular dosage do you think it still needs a doulbe dose?

Also i read on the other site that dfi motors are voltage sensitive......last time out while starting my motor my gps gave me a "low voltage" prompt. I have found that while running my volt meter is at 13.2 volts, with the engine off i am at 12.2 but when i turn the key to start the engine the volts drop anywhere from 11.2-11.6. Is that normal drop in volts when a motor starts? If not could that make me stall shifting in and out of gear from idol?? Thanks!

[blueh20pc]

Have you got a bad plug cap, Maybe some corrosion inside the boot?

Check your boots, the plugs are good but maybe something gummed up the contact from boot to plug.

Unless HPDI's are coil on plug ignition, I'll bet you got some crap shorting out a plug somewhere,

[2 Bit Hook'R]

I have a 300 and have had similar issues, but they have always been fuel related.
water seperator filter, then engine filter, then there is a filter that only a yamaha dealer can replace, it is a vapor filter (vst or vsx) ? they will know what your asking about! also have you been burning straight gas or are you burning gas with ethynol? they say you must shock your existing fuel during your 1st 3 fill ups. here in N.C. it just started showing up at the docks. they say you should not use one then the other! has something to do with water break down in your tank. just a few thoughts! Jim

[SKEETERMAN]

I'll theck the spark plug boots. The VST is the only filter that you mentioned that i havent changed and ill do that this weekend. The boat has only been run on e-10 since it was new and i know thats not the problem. I am curious if anyone knows if thats a normal volt drop when starting becuase i have read that if the engine is volt starved it can cause plug problems, stalling, fouling etc. Thanks guys!

[glen e]

the voltage is worth a shot - I think all new gen motors like volts - remember at 12.0, you are 50% discharged on a batt....this is verado stuff but it still applies on batts:

Verado Voltage Test

[SKEETERMAN]

Thanks Glen. I know i am at 12.2 at rest which is low according to your data (60%). I haven't tried the heavy load and waiting 10 minutes part yet but ill do that tomorrow.

[Garett]

Originally Posted by SKEETERMAN

I have found that while running my volt meter is at 13.2 volts, with the engine off i am at 12.2 but when i turn the key to start the engine the volts drop anywhere from 11.2-11.6.

What do I know, 11.6-11.2, I'm surprised the engine turns over and starts. How are you reading these figures? Is your gauge digital? Once the engine is running at idle what is the voltage? Your stalling problem could be that the engine is voltage starved at low rpm.....those on board alternators don't pump out much voltage....especially at low rpm.

About those plugs you are buying, are they the cheapest plug you can buy but still a brand name? The cost of plugs has everything to do with my question. I know with Champion spark plugs they have six different grades of the same plug. To the best of my knowledge as a consumer one would have to be able to decipher the bar code to be able to distinguish the difference between one grade and another, the packaging all looks the same to me. Grade six is the worst, but the cheapest to buy. When I didn’t know any better and I was buying the cheapest ones I usually had to buy a dozen to get eight good ones and of those eight so called good ones some of them “might” last a mile or two, I’ve even burnt the entire ground strap off the plug in less then fifty miles. My bottom line now-a-days is, I never bargain shop for plugs.

Good luck with sort this out.

[SKEETERMAN]

Originally Posted by Garett

What do I know, 11.6-11.2, I'm surprised the engine turns over and starts. How are you reading these figures? Is your gauge digital? Once the engine is running at idle what is the voltage? Your stalling problem could be that the engine is voltage starved at low rpm.....those on board alternators don't pump out much voltage....especially at low rpm.

About those plugs you are buying, are they the cheapest plug you can buy but still a brand name? The cost of plugs has everything to do with my question. I know with Champion spark plugs they have six different grades of the same plug. To the best of my knowledge as a consumer one would have to be able to decipher the bar code to be able to distinguish the difference between one grade and another, the packaging all looks the same to me. Grade six is the worst, but the cheapest to buy. When I didn’t know any better and I was buying the cheapest ones I usually had to buy a dozen to get eight good ones and of those eight so called good ones some of them “might” last a mile or two, I’ve even burnt the entire ground strap off the plug in less then fifty miles. My bottom line now-a-days is, I never bargain shop for plugs.

Good luck with sort this out.

I didnt check the rpm's at idol but i guess i should have. The voltmeter is yami multi-function digital. I did Glens ten minute test today and after ten minutes my volts only rebounded to 12.0. I will buy a new sears diehard platinum agm battery tomorrow. Battery definately needs to go i hope it cures my stalling problem as well. I am surprised it hasnt failed on me as well. I do a lot of drifting with my panel on with two depthfinder/gps and one vhf on all the time. I know they dont draw much but with a bad battery i guess i am lucky.