1997 Mercury EFI 250 spark plugs??

[Tinbanger1979]

So what plugs is everyone running and having good luck with? I have a 1997 Mercury 250 EFI, 300 ProMAx heads,and 300 ProMax computers, and wondering what plugs to run? I have been running Champion QL77CC plugs, but thinking about getting the NGK BR8HIX 7001 to try out and hope they might not foul out while in wake zones. My motor is setup to premix and sometimes i'm a little heavy on oil since my tank is below deck and 82 gallons.

[Varmint]

I never had issues with the ql77's,but i have a 250xb with 300pm ign. And 250xb fuel ecu. I would try running it with the stock fuel ecu,all the 300pm ignition ecu does is raise the rpm limit. Your fuel ecu may be running too rich @ wake zone rpm. The 250xb fuel ecu has been proven to run best with 300ign ecu on the non hi po 225/250 powerheads

[Tinbanger1979]

I'll keep running the QL77CCs in my motor. So what's the main difference between the 250 XB and the 250 EFI fishing motor fuel ECUs curve? I was thinking about sending my 250 EFI to Simon and have it reprogrammed to 250 XB specs. I also have a 300 ProMax motor, but it's on the back burner for now.

[RSWORDS]

I'll keep running the QL77CCs in my motor. So what's the main difference between the 250 XB and the 250 EFI fishing motor fuel ECUs curve? I was thinking about sending my 250 EFI to Simon and have it reprogrammed to 250 XB specs. I also have a 300 ProMax motor, but it's on the back burner for now.

I *think* (and maybe someone that knows more will correct me) that the XB computer doesn't go stupid rich at WOT/higher RPM like the regular 250

[Chaz]

thinking about getting the NGK BR8HIX 7001 to try out and hope they might not foul out while in wake zones.

BR8HS plugs can be found on sale for less than $ 2.00 ea. Early model ign, squeeze the gap down to .030 and don't look back ..

Chaz = thinkin it cost more for 1 chumpion than a box of 10 NGK's

If your muffler looks like this , like you like for sure like need like wire like plugs like.

Otherwise, like save your money ... Or better yet, talkin bout wire ... >
Throw away them 22 year old plug wires that prob measure 15,000+ ohms and buy a set of Summit or Jegs house brand 8 mm spiral core build your own wires for a 6 cyl with a HEI ign for $ 38 Comes with the boots already on them. Just put the CDM side on ... and there's enough left over wire to build another set down the road ... just buy ends

[Tinbanger1979]

I found the champions QL77CC for $3.88 a plug for a 6 pack. I like the Ideal of building my own wires from the 8mm spiral kits from Jegs/Summit, probably better quality than OEM. I did replace my coils and wires with OEM Mercury stuff last fall, so hopefully I don't need them wires yet.

Don't know about the exhaust comment, but I run a borla exhaust on my Cadillac Escalade ESV and my F250 crewcab 6.0 got straight piped duals rollin coal.

[Motv18]

Try the nex heat range up ql8_cc 80-89

the 77 is slightly cooler then the ngk b8 or br8 that many run.

[Chaz]

I found the champions QL77CC for $3.88 a plug for a 6 pack. I like the Ideal of building my own wires from the 8mm spiral kits from Jegs/Summit, probably better quality than OEM. I did replace my coils and wires with OEM Mercury stuff last fall, so hopefully I don't need them wires yet.

Don't know about the exhaust comment, but I run a borla dual exhaust on my Cadillac Escalade ESV and my F250 crewcab 6.0 got straight piped duals rolling coal.

If you have already dealt with the ignition side ..

Then if you haven't thrown away ... err .. cleaned the little screen ( how many filters does a fella really need ) under the regulator. Now would be a good time to do it.
The bad rap the early model's have for burnin fuel, while you have the "chrome dome" reg off, convert it to an adjustable. Squeeze a couple pounds of running pressure out of the system. You'll be amazed at how well it will clean up and it's a little cheaper than playin musical fuel box's that do .... nothing .

Iridium plugs ... my truck started skippin .. it's the injectors . It's the coil packs .. It's bla , bla , bla , tester said lean miss ... Took the injectors to my injector guys , they blew some **** thru them , got a flow sheet , no suprize's there.
Two plugs on the right bank burned the little wire back to the porcelain . Put REAL plugs and a new set of wires on .. Ohh and I gotz a spare set of coil packs in case the wives tale ever comes true ...
B-sides - ya ever tried ta spray nitrous on top on an extended tip wire plug .. Ppffftttt ... gotta be why them NAwzZ kids have faRt can mufflers .. bOOm

[Tinbanger1979]

Chaz, that's funny you mention about the screen under the pressure regulator. I was thinking about throwing it away. So how many fuel filters are needed, 1 screw on 30 micron Yamaha filter in my boat, 1 mercury fuel filter on side of the motor, one on the HP fuel pump, and in the pressure regulator?

Plus I like saving money on reprogramming fuel boxes.

[Chaz]

Don't forget , 6 more lil basket filters in the injectors ...

[rock]

Funny you would mention the filters. Just asembled a 200 and it would start and run for 20 seconds or so then die. Took regulator apart and it was 95% plugged with sludge probably from previous boats fuel system. Also had Power do the injectors and reassembled without screens,. Runs like a top now.

Rock

[Varmint]

If you have already dealt with the ignition side ..

Then if you haven't thrown away ... err .. cleaned the little screen ( how many filters does a fella really need ) under the regulator. Now would be a good time to do it.
The bad rap the early model's have for burnin fuel, while you have the "chrome dome" reg off, convert it to an adjustable. Squeeze a couple pounds of running pressure out of the system. You'll be amazed at how well it will clean up and it's a little cheaper than playin musical fuel box's that do .... nothing .

Iridium plugs ... my truck started skippin .. it's the injectors . It's the coil packs .. It's bla , bla , bla , tester said lean miss ... Took the injectors to my injector guys , they blew some **** thru them , got a flow sheet , no suprize's there.
Two plugs on the right bank burned the little wire back to the porcelain . Put REAL plugs and a new set of wires on .. Ohh and I gotz a spare set of coil packs in case the wives tale ever comes true ...
B-sides - ya ever tried ta spray nitrous on top on an extended tip wire plug .. Ppffftttt ... gotta be why them NAwzZ kids have faRt can mufflers .. bOOm

Not to change subject,but my lil 4.8 chevy truck motor gives me the lean burn on left bank code, i know these motors use iridium plugs,you think that and new wires will be the culprit ? It doesnt really skip or run rough,small miss @ idle maybe i'd say

[FORBESAUTO]

Not to change subject,but my lil 4.8 chevy truck motor gives me the lean burn on left bank code, i know these motors use iridium plugs,you think that and new wires will be the culprit ? It doesnt really skip or run rough,small miss @ idle maybe i'd say

Those things are bad about intake gaskets leaking on the center cylinders mainly when cold before it expands. Caused by a combination of warpage of the plastic intake and rubber strips flattening out in the plastic backed intake gaskets. Fel-pro makes a thick rubber gasket with metal in the middle of the rubber to fix the problem. http://www.jegs.com/i/Fel-Pro/375/MS98016T/10002/-1

[Tinbanger1979]

[QUOTE=Chaz;3121356]If you have already dealt with the ignition side ..

Then if you haven't thrown away ... err .. cleaned the little screen ( how many filters does a fella really need ) under the regulator. Now would be a good time to do it.
The bad rap the early model's have for burnin fuel, while you have the "chrome dome" reg off, convert it to an adjustable. Squeeze a couple pounds of running pressure out of the system. You'll be amazed at how well it will clean up and it's a little cheaper than playin musical fuel box's that do .... nothing .


Chaz, you got any more details about converting to an adjustable fuel regulator? I had a big JOHNSON 300 V8 with a Holley red fuel pump and a bypass regulator with a return line going back to my tank when I first got my boat. You talking something like that or tear off the " chrome dome" and install a dead head bypass regulator? I would love to use less fuel and have a cleaner running motor, well as clean as it gets with dinosaur oil. LOL

[Chaz]

The details are as follows ..
All that stuff is made by Keihin which is owned by Honda. So any of those kits for a 88 to 05 civic ( fart can car ) will work .
I use the one from BLOX racing . bxfu

https://bloxracing.com/shop/index.ph...product_id=162

Jegs , Summit , flee-bay sells em pretty cheap .

Early models had a chrome dome, zip that thing off like a can opener .. but leave the crimp . Late models were alum tops .. They all take a little height adjustment or hole size to get right depending on year .



The 300x VST tank was left blank and they used an antique 200 type body on the fuel rail. With a little hook on the return side that went thru an air hole to the other side and back to the tank. When they became NLA from the factory , I scrounged up a bunch of them and made a straight stainless stem and threaded it into the body as a replacement. Took a little longer hose, because it had to go around the bottom ..

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