No power

862 Views 39 Replies 9 Participants Last post by GDCobra, 15 d ago

miata76

Discussion Starter · 1 mo ago

2003 SV1000 OEM Naked.
Engine starts fine.
Won’t reach 60mph. Will only reach 55mph in 5th gear (not 6th)
Limited power below 3,000 rpm. No power above 3,000 rpm.
Fuel flow was a bit low (8oz after three prime cycles).

Bypassed embedded fuel filter via 45 degree angle drilling of pump assembly. Installed 10 micron inline filter between pump & throttle bodies. No improvement in power.

Replaced fuel pump & fuel pressure regulator. Now three prime cycles produce closer to 15oz of fuel (post filter). No improvement in power.

Trying hard to remove fuel rail - proving difficult (soaking in penetrating oil). Any ideas as to the best way to remove fuel rail screws?

If fuel injectors are bad, is there a rationally priced replacement?

Does the group think I’m on the right path?

Any other ideas?

Thanks!

21 - 40 of 40 Posts

miata76

Discussion Starter · #21 · 25 d ago

GDCobra said:
Great news, good to hear of another SV heading back to full health and another SV owner heading back to full happiness! Gotta love that feeling when you solve a problem.

BTW, I'm judging by your monika that you have some association with the wonderful Mazda car? Which model do you have/had?

Miata: I’ve purchased two (both new: ‘93 & ‘11). Loved them both; still driving the 2011. The Miata/MX-5 (roadster)experience is not really all that dissimilar to a motorcycle & would I not hesitate to purchase another. 😉

I had a VW Eos (retractable hardtop) in between while living in cold, cruel New Jersey. The car was (in my experience) nowhere near as reliable as the Miata & VW (corporate) customer service left a little to be desired (again, in my experience).

Do you have a convertible?

GDCobra

· #22 · 25 d ago

miata76 said:
Miata: I’ve purchased two (both new: ‘93 & ‘11). Loved them both; still driving the 2011. The Miata/MX-5 (roadster)experience is not really all that dissimilar to a motorcycle & would I not hesitate to purchase another. 😉

I had a VW Eos (retractable hardtop) in between while living in cold, cruel New Jersey. The car was (in my experience) nowhere near as reliable as the Miata & VW (corporate) customer service left a little to be desired (again, in my experience).

Do you have a convertible?

I currently have a 2013 (NC) power hard top MX-5, previously had an '06 (early NC) soft top. They're a great little car, not over endowed with power but like a go-cart to drive, very direct brakes, steering and so on. Also relatively simple and easy to look after myself.
We've just got rid of a Mercedes SLK 55, obviously a lot more sophisticated but not necesarily more fun.
I have an AC Cobra kit car which makes the Mazda feel like a luxury barge, everything is very direct on that car.

Reactions: 2

miata76

Discussion Starter · #23 · 22 d ago (Edited)

UPDATE

About 150 miles ridden since “clutch switch fix”. Bike has recovered somewhat.

@ Bike will get to 70mph (77 indicated), but only in 5th gear. There’s not enough power to maintain 70mph in 6th gear.
@ Bike will maintain 60mph (66 indicated) in 6th gear.
@ Miles Per Gallon had dropped from “north of 35mpg” to “south of 20mpg”. Fuel does not appear to be getting to the crankcase (oil level essentially stable).

Is there a lengthy “computer relearn” process in these bikes that could be contributing to the poor gas mileage? Are there settings on the throttle bodies that need to be adjusted to address the improved fuel flow?

By The Way - Throttle position sensor was checked & is “spot on”.
By The Way 2 - Coolant temps remain about 160 degrees Fahrenheit highway & 180 - 190 degrees Fahrenheit in stop & go city traffic (w/ambient between 85 - 90 degrees Fahrenheit). I would expect higher coolant temperatures if there was excessive blow by or the oil pump was failing (but I could be very wrong in my thought process).

A leak down test was previously suggested. I’ve not done one on a motorcycle - After TDC is substantiated, is it just a matter of dropping it in gear & have someone hold the rear brake?

Is there anything else I should be looking at?

Thanks!

See less See more

Missing Link

· #24 · 22 d ago

I dont believe there is any learning done by these things.....bit archaic for that.

The leak down is proabably the next tell....

You are running the right plugs ? CR8EK ? you haven't got 9's in it ? Lower the number hotter the plug. Those running temps are "maybe" a little cool......
Mine ran at 175 (weird talking in F deg), and getting caught in heavy traffic would result in around 200

miata76

Discussion Starter · #25 · 22 d ago (Edited)

Computer: Thanks for the “no learning” confirmation. It seemed to be going on too long for anything this old.

Coolant temp: The coolant temps reflected above are substantially cooler post changes (new fuel pump & refurbished injectors - engine running too rich?). Temps prior to changes were much closer to ML’s (fan would engage at a traffic light - 212F/100C).

Plugs: I’m running the recommended plugs (I don’t recall the number); however, it would make sense to change them at the leak down test (cheap). Would you recommend “hotter” plugs for these symptoms?

miata76

Discussion Starter · #26 · 19 d ago

Wood Curious Auto part Musical instrument Audio equipment

No Power Update.

It took a while to locate a 10mm leak down adapter (I had to purchase a cheap compression tester & wait for delivery).

Leak down: Both cylinders were 80/80 - could have been 78/80 - done alone. Regardless, the engine would seem to “pass” this test.

Note: I’m not certain what it means (diagnostic value?), but I was not able to find the timing mark for the front cylinder. I had to rely on ”compression detection” & “dialed it in” using a breaker bar.

Compression: Because I had the tester . . . Both cylinders were “north of 114lbs” after three cycles and were continuing to climb. Again, this would seem to “pass”.

I’ve attached a pic of the spark plugs for diagnostic purposes. They were the proper heat range, but were Iridium (prior plugs had (carbon) fouled out due to clutch switch failure reflected earlier in thread) - as I seem to recall, since plug swapping is a bit “fiddley” on these bikes, I opted (@ the time) for the more “foul resistant” plug.

Someone, w/o looking at the bike, suggested “vacuum leak”.

Does anyone have any thoughts?

Is there a vacuum system on these bikes?

See less See more

flashslburg

· #27 · 19 d ago

Judging by the candle, the mixture in the rear cylinder is richer than in the front one. Maybe the nozzle is leaking?

miata76

Discussion Starter · #28 · 19 d ago

FIXED!!

Spark plugs replaced & placed oversized silicone caps (the only size I had) place OVER the rubber “throttle body synchronization caps”.

In the midst of all my frustration, it didn’t occur to me until after the last post that the throttle body synchronization process is VACUUM. If the caps have rotted then there could be a “vacuum leak”.

It now has more power than when I bought it!

Does anyone know the sizes of the throttle body sync ports (the double layer is merely a temporary test of concept)?

GDCobra

· #29 · 19 d ago

miata76 said:
FIXED!!

Spark plugs replaced & placed oversized silicone caps (the only size I had) place OVER the rubber “throttle body synchronization caps”.

In the midst of all my frustration, it didn’t occur to me until after the last post that the throttle body synchronization process is VACUUM. If the caps have rotted then there could be a “vacuum leak”.

It now has more power than when I bought it!

Does anyone know the sizes of the throttle body sync ports (the double layer is merely a temporary test of concept)?

Good to hear. I think the sync' pipes are 4mm, I ordered some caps from ebay just over a year ago for mine, unfortunatley I can't see the original ad' to get the size, I'll check the garage tomorrow and measure if that's any good. The caps I got were larger OD (but standard ID) than standard and gave a more secure fit. I think they were also silicone.

The area around the edge of that rear plug seems to have some damage, any idea what that is?

Never done a comp' test on the bike, when I do it on the car I spin until max' pressure is reached (and count the turns) with all plugs out (for max' engine speed) and open throttle.

114 sounds a little low (normally told should be over 150 on a car engine) but this could be because of the performance orientatoin of a bike engine with longer valve opening.

Reactions: 1

Tom1975

· #30 · 19 d ago

Welcome here

Sent from my TECNO KC8 using Tapatalk

Reactions: 1

Missing Link

· #31 · 19 d ago

GDCobra said:
..................................The area around the edge of that rear plug seems to have some damage, any idea what that is?

Have to ask the same question....whats up with the rear plug......those little dings around the edge ?
They look llike damage, but, they are too regularly spaced. Never see that before on an NGK, if it is....

The are both CR8EK NGK's ?

Reactions: 1

miata76

Discussion Starter · #32 · 19 d ago

Spark Plugs: Both were the Iridium equivalent plug to CR8EK.
Rear Plug: I believe the film & particles on the plug are the result of the excessively rich mixture (days later much of the film had evaporated). It was running so rich that I had to drain 1.5 quarts of “crankcase fluid” (excess gasoline was draining into crankcase over time) to ride it today (to verify fix). I’ll change the oil tomorrow. Going forward, I’m guessing it will burn cleaner.
Note: Plugs swapped to CR8EK (normal, non-iridium).

Missing Link

· #33 · 19 d ago

NGK are probably the best plugs in my opinion.

As far as the excess fluid, to get that much fuel into the oil, the injector would have to have been squirting like a hose.
Or, at worst, the injector was stuck open, and, unlikely, the fuel would have to have been draining form the tank....

But, anyway, we will see what happens.... it may be worth throwing some cheap disposable oil in and running the engine to flush it
free of any of the contaminated oil. Drain the old oil filter properly and put it back on for this step.
Then put in the good stuff and a fresh filter

Reactions: 1

miata76

Discussion Starter · #34 · 19 d ago

Old Spark Plugs (in pic): NGK CR8EIX (Iridium).

Cheefddrl

· #35 · 19 d ago

The rail screws are a B+t$h first ime....change them for allen heads.... Make sure you have a JIS screwdriver, and tap the end of the screwdriver with a hammer while you have tension
on the screw......an impact driver may help, but, push hard.

miata76

Discussion Starter · #36 · 18 d ago (Edited)

Low Compression: The Suzuki manual lists 114lbs as a minimum. So, when I was able to verify that it was more than that after three revolutions & continuing to climb, I stopped the test.

I should have been more clear.

Reactions: 1

yemekim794

· #37 · 15 d ago

Just a fuel injection specialist

Sent from my TECNO KC8 using Tapatalk

GDCobra

· #38 · 15 d ago

miata76 said:
Low Compression: The Suzuki manual lists 114lbs as a minimum. So, when I was able to verify that it was more than that after three revolutions & continuing to climb, I stopped the test.

I should have been more clear.

I wouldn't really say 114 is low necessarily, all engines are different. The Rover/Buick based V8 in my kit car "only" manages just over 150PSI whereas others suggest they get 180PSI or more. My engine is not in bad shape so why does it seem low? I can only suggest this is because mine has a longer duration cam which means inlet valve is held open longer as the piston is charging up the bore on compression, seems like a bad idea until you take into account the fact that the inlet charge also has inertia to overcome this. However the inertia is poor at low engine speed so when taking a compression reading at cranking speed I'm not getting a full cylinder before the inlet valve closes, at higher engine speeds (hopefully) the positions will reverse and my engine will get more air in due to the longer opening.

As I say I'm not to familiar with bike engines but they obviously do employ higher RPM, even idle speed is about double that of my V8 and max speed is also getting on for double so a lower comp' test reading may be to be expected. Next time I change spark plugs I'll try and do a comp' test and see what mine gives.
Pity you didn't max out the reading though, it would have been interesting to know what it could have got to.

See less See more

Missing Link

· #39 · 15 d ago

Starter motor speeds give a "static", for want of a better term, pressure reading....the true result from a full speed idle is probably a good bit higher i would assume

Reactions: 1

GDCobra

· #40 · 15 d ago

Missing Link said:
Starter motor speeds give a "static", for want of a better term, pressure reading....the true result from a full speed idle is probably a good bit higher i would assume

Exactly, all depends on the nature of the engine, if it's tuned for maximum bang at high RPM then it'll be deficient at lower RPM (variable cam timing aside)

21 - 40 of 40 Posts