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Stalls after 3 seconds....HELP Seems like regulator


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So my 98 sunsetter monsoon efi ran great up until the other day it stalled on the way to the ramp and would only start for 2-3 seconds then stall....and still does.

So I changed both filters, changed distributor cap and rotor. I have good spark but now for where Im scratching my head.

It has 45 psi fuel pressure during the key prime cycle... if i hit it again it will go to 80psi. It will start and run if i dump the line to 0...when its at 50psi a few seconds after starting it runs then the fuel pressure gauge goes up to 85-90 psi and the engine stalls.  I took off the regulator seems ok fuel goes through it and diaphragm seems ok when sucking on it. Fuel pump intake screen is clean...

Heres where im stumped...if i dump fuel from the fuel pressure gauge pressure release back on the fuel rail into a jug it runs at about 45 psi and idles from 650 to 850 but obviously rough....would that point to a regulator? I searched online and it seems bosch has discontinued my regulator p/n 0280160237 unless I didnt see a new part#

It also seems to have alot of suction sound from the carb with the arrestor off the scan tool i have says 18-20 in-Hg so thats fine from other engines I work on...but i dont recall it sounding like that prior probably not anything. Throttle is completley closed with this noticed sound.

When i removed the fuel pump i noticed a orange looking ball/check valve in the pump on the return side Im guessing either that is stuck not allowing unused fuel to be reused or the regulator is bad somehow blocking fuel...but fuel flows through it when its a key on senario so Im stumped.

Would the regulator not be closed with no engine vacuum it seems to be the opposite. Seems to me that it should work as the more vacuum the more it opens to allow fuel thru.

 

Any help would be great!

 

Jason

 

Edited by greenworks
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The fuel regulator has nothing to do with manifold vacuum.  The regulator keeps a constant pressure on the fuel rail by returning excess fuel to the tank via the return line.  The fuel rail needs constant pressure because your engine runs open loop, meaning that the ECM uses an educated guess to calculate how much fuel to squirt each rotation by measuring engine load and then timing the squirt assuming a known fuel pressure.

Since you don't have constant pressure, I think you have a bad regulator.

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I am thankful for the expertise on this forum. I am kinda surprised it stalls. It sounds like it has enough at pressure at idle. Too much ?

Steve B.

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So doing more testing it seems to be a high vacuum issue. Starts at 10-12 Hg then slowly climbs upto 26Hg at idle before stalling 15 second or so. I've blocked the vacum to the regulator it seems to run longer

 

What would cause vacuum to build? 

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The regulator has a vacuum hose attached to it I assume at low vacum or WOT it opens to allow more fuel to rail or restricts which ever way it's setup...

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Just some data...my Techmate tool says...

timing is at 9.8 advance 

Fuel flow 3.8-4 gph

No codes present

 

 

Man this is weird...1st time in 13 years of owning this boat its ever let me down on tbe lake and this is a puzzle!

Giving up for tonight...just my luck a warm stretch this week and i have a 21' canoe...cry

 

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2 hours ago, greenworks said:

So my 98 sunsetter monsoon efi ran great up until the other day it stalled on the way to the ramp and would only start for 2-3 seconds then stall....and still does.

So I changed both filters, changed distributor cap and rotor. I have good spark but now for where Im scratching my head.

It has 45 psi fuel pressure during the key prime cycle... if i hit it again it will go to 80psi. It will start and run if i dump the line to 0...when its at 50psi a few seconds after starting it runs then the fuel pressure gauge goes up to 85-90 psi and the engine stalls.  I took off the regulator seems ok fuel goes through it and diaphragm seems ok when sucking on it. Fuel pump intake screen is clean...

Heres where im stumped...if i dump fuel from the fuel pressure gauge pressure release back on the fuel rail into a jug it runs at about 45 psi and idles from 650 to 850 but obviously rough....would that point to a regulator? I searched online and it seems bosch has discontinued my regulator p/n 0280160237 unless I didnt see a new part#

It also seems to have alot of suction sound from the carb with the arrestor off the scan tool i have says 18-20 in-Hg so thats fine from other engines I work on...but i dont recall it sounding like that prior probably not anything. Throttle is completley closed with this noticed sound.

When i removed the fuel pump i noticed a orange looking ball/check valve in the pump on the return side Im guessing either that is stuck not allowing unused fuel to be reused or the regulator is bad somehow blocking fuel...but fuel flows through it when its a key on senario so Im stumped.

Would the regulator not be closed with no engine vacuum it seems to be the opposite. Seems to me that it should work as the more vacuum the more it opens to allow fuel thru.

 

Any help would be great!

 

Jason

 

High fuel pressure indicates a bad fuel pressure regulator. You mention it runs when you bleed off pressure. At idle you should see 35-38 psi.   Mine used the same part number, I think I found the replacement at NAPA.

Edited by Bozboat
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12 hours ago, greenworks said:

So doing more testing it seems to be a high vacuum issue. Starts at 10-12 Hg then slowly climbs upto 26Hg at idle before stalling 15 second or so. I've blocked the vacum to the regulator it seems to run longer

 

What would cause vacuum to build? 

 

12 hours ago, greenworks said:

The regulator has a vacuum hose attached to it I assume at low vacum or WOT it opens to allow more fuel to rail or restricts which ever way it's setup...

OK, sorry, I misspoke.  The regulator *does* have something to do with vacuum, but in your case I think that the regulator diaphragm is leaking and changing both the fuel pressure and the manifold vacuum.

Your engine is designed with 3 Bar injectors, which means that they want 3 atmospheres of pressure on them at all times.  That's 14.7 PSI * 3 = 44.1 PSI on the fuel rail nominally.  If you have less pressure, the engine runs lean.  If you have more pressure, the engine runs rich.

It is possible that the vacuum hose is cracked and leaking, so double check the manifold to make sure that everything is OK and the hoses are good.  After that, change the regulator.

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Problem solved it was the regulator, the only issue its is discontinued in every variety in Canada anyway unless you wait and order from Indmar for 250US. I sourced a similar regulator and replumbed the return lines to the tank and blocked of the pump inlet where the return fuel goes...the retro fit fuel pump does not have a return inlet either do i figured might as well start the process. 

 

Anyway runs like a champ with a steady fuel pressure. Lake test tommorrow....hoping for the best 

 

J

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  • 3 weeks later...

I ended up using a Standard Motor Products PR60 regulator. The mounting bolts line up and the Oring insert fits well. The only modifications are the fuel line and its  straightforward simple job. Been running really well for several lake trips.

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