2001 Honda RVT 1000, Honda RC51 Fuel Problems

Vehicle: 
2001 Honda RC51

Problem: 
Poor mileage and poor performance. This motorcycle was spectacular in it's debut. I picked it up from a friend who hadn't ridden it in years. It sat in his garage, had been dropped and even rebuilt after a crash once. The issue with this motorcycle was poor performance, skipping throttle response, and running rich. At throttle, the bike would hesitate, as if it were running on a single cylinder instead of two.

Test Drive: 
At highway speed the bike would move along, and then die, then kick on, die and then fire, die and then fire. It was a constant hiccup when driving down the road, that happened occasionally, but became worse over time. It was as if the engine governor would kick in even though you were nowhere near the redline. The engine would die, and then resume power repeatedly. Frustrating when you're on a trip between states, let me tell you!

Diagnosis: 
At first I thought the problem was electrical, and so replaced one of the coil packs. This didn't resolve the issue. After some online research I saw some poor souls being ripped $2000 for a new fuel rail assembly, which did indeed cure their problems. The same problem I was having. However.... as a do it your selfer.... I find it hard to part with $2000 when the only components on the fuel rail consists of a few injectors, piping, and a fuel pressure regulator. It took me some time to bite the bullet to even think of parting with $2k just because some shop or even Honda recommends it. There had to be something else!

Fix:
Further troubleshooting..... gasoline is comprised of an ethanol mix these days, made of corn oil derivatives. Corn oil gets sticky when it's overheated, much like when you overheat corn oil in a frying pan. The design of the RC51 fuel system is that the fuel rail sits on top of the engine in a confined area, with poor air circulation. heat rises and slowly cooks that fuel pressure regulator after you've turn the key off and parked your bike.  The residue buildup acts like plaque in your arteries as the residue clings to the interior of the fuel rail pipes and the fuel pressure regulator. Ever seen your lawn mower float bowl in the carburetor after it's been sitting over a winter? It's like that. Buildup of residue. Enough with the justification already,, lets move on....

The problem with the fuel rail assembly isn't with all of the components. Honda might suggest a new fuel rail assembly to save their technicians time in diagnosing the root cause. The problem as in my case, was with the fuel pressure regulator. The gasoline in the system had been sitting in the bike in this guys garage for two years or more. Internal residue is nearly impossible to get rid of or clean out of your fuel pressure regulator. Cost for a new regulator runs about $50.

Find and order one here..
HONDA REGULATOR, PRESSURE - order part here

1. Work on your bike when the engine has cooled off. Lift your fuel tank up.
2. You might be able to access it without removing your air box. I recommend removing the air box to get full view of the fuel rail assembly. So... remove the air box.
3. Place a shop rag beneath the fuel pressure regulator. Hang some of the shop rag over the top of the fuel pressure regulator to catch any fuel spray as you remove the fuel pressure regulator. Use an open end box wrench to remove the fuel pressure regulator. Rotate the wrench counter-lock wise (righty-tighty, lefty-loosey) to loosen it. Unscrew the old one out with your hand.
4. Screw a new one into place. Do you need teflon tape? Not likely. Just reassemble with all components (washers etc...). Use new washers if you prefer, and, IF there is one. I can't remember, it's been awhile.
5. Tighten the new fuel pressure regulator into place with the wrench. Don't monster tighten it, but you do want it tight.
6. Key on, to test the fuel pressure in the system and check for leaks. With the tank up, and fuel lines connected, turn the key on, and pressure should build up. Look for any leaks at the fuel pressure regulator fitting. If there are none, cycle the key on/engine off several times to build up proper fuel pressure within the fuel rail. If no leaks occur, then you are good to go. It's tempting to start it up right now, and if you do, for goodness sake, remove all your tools, screws, bolts, loose components and shop rags from the intake path and throttle bodies so they don't get sucked in there and cause all sorts of horror.
7. Reassemble the air box, remove any other tools and rags. Lower your tank, button it up, and take your baby down the road for an obnoxious roar or two!
8. Check for leaks over the next few days or rides. You can never be too careful. The last thing you'd want is to ride down the road with your crotch on fire.



Post work assessment:
Problem solved with the new fuel pressure regulator installed. previously my problem was sooooo bad I was getting 3mpg. No joke, it sucked! With the new regulator installed, everything was fine, fuel economy if you can call it that with this bike, had returned. No more skipping throttle response, no more dead throttle spots. Everything was great! And I saved $2000!

Hope this helps someone out there!

2002 PT Cruiser Over heated and related electrical problems relating to cooling systen

Car: 
2002 PT Cruiser

Problem: 
1. Overheats, blown head gasket.

2. Electrical issues relating to proper cooling, voltage regulation, and transmission problem.

3. Engine vibration

Test Drive: 
No test drive, Dead on arrival.

Diagnosis: 
      This car came to me with a blown head gasket. And later overheated again after the head gasket was replaced, with  a new thermostat and new water pump. This was an incredibly difficult diagnosis, because it isn't typical for a car to overheat after replacing major cooling components where it would lead to a major electrical problem within the car itself within the same malfunction. The root cause was electrical, where the initial diagnosis was a problem with the cooling system.

Fix:
Car came to me dead on arrival. Removed the engine due to limited work space in the engine bay. New head gasket installed. New water pump, new thermostat. Radiator didn't appear to be clogged as the coolant wasn't dirty or yucky coming out of the drain tube. If there had been residue buildup, I would suspect clogged plumbing. But there was none. With the head gasket replaced and passenger sidewall engine mount replaced, the engine was re-installed. Test drive indicated the cooling problem was resolved. Drive to the dealership to return the car and the car is overheating, boiling over. After much research and troubleshooting a few days later, I find a single post out of 100 that indicate the problem might be with the electrical system failing to turn on the cooling fans. But why?

Further diagnosis with the car....

Headlight dimming. Car idling funny when shifting into gear from P. Interior lights flickering. All of this indicates it may have a weak battery. New battery installed, and same symptoms still persist. Install a used alternator. Same problems still persist.

Further troubleshooting electrically.... Voltage meter on the battery reads proper output voltage from the alternator. and battery voltage. What gets me is that the headlights dim when you turn them on, and the engine idle dies down when you go to high beam. Turn on the AC and it idles even more roughly. Put it into gear and it almost dies.

Root cause analysis:
After all of this work, the problem is related to the electrical system. While the original head gasket did need to be replaced, the root cause of the problem is voltage regulation. After thorough troubleshooting, as this was a doozy to fix.... the root issue was with the car's main computer. Chrysler decided to put the voltage regulator in the main computer box. What was happening was that as the car idled, the voltage regulator was able to keep up with demand, however if you loaded the electrical system down by turning on the high beams, the AC unit full blast, and shift the transmission into gear, the computer has to decide which system to keep alive, and will shut down all unnecessary functions. The computer was resetting itself  when the voltage/current demand was not enough to keep the main computer functioning, which caused the rough idle. When it resets, the idle air control system had to hunt for it's proper setting because, at the moment of reset, it did not keep in memory where the idle air control valve position. With lights flickering, and when the car's electrical load increased due to being in gear, the AC unit on, the system would reset. It could not regulate voltage properly, dropping voltage below the 5VDC threshold required to run the system computer.  Research and discernment to the root cause was that the internal voltage regulator in the main computer was failing.


THE FIX: 
After the head gasket was replaced and new thermostat and water pump installed, and the engine installed into place, and after further diagnosis with the electrical system......

The main computer in the car needed to be replaced. This Chrysler car main computer box is filled with a gelatinous substance, and the metal box is the heat sink, which is bolted to the rear firewall.

I ordered a used vehicle ecm from a company out of Florida via website. They needed the VIN code, and the mileage. Given that, and free shipping, the first computer they sent me was a refurbished unit that failed to even start the car. So I won't recommend them, or give their name here. The replacement computer arrived after another week of waiting for free ground shipping. I tell ya, customer service used to mean something, but not to these folks in Florida at this company. With the second car computer in hand, programmed with the right VIN code and mileage.... the car started up. The cooling fans came on properly, and the lights no longer flickered. The vehicle, even under full load with the AC running, car in gear, high beams on, and cooling fans running, the car held up and didn't die.

Post work assessment:
Everything on the car was working as it should have been. The cooling fans kicked on at the proper temperatures. The electrical system was no longer getting bogged down, and the idle was running smoothly. I had to make a minor adjustment to the engine tilt due to the new engine mount to eliminate engine vibration.

Like I said, this was a doozy of a problem car. While everything pointed initially to a cooling problem with this car, the end result turned out to be a problem with the main computer. Who would've thought? If I didn't have my 15 years of experience as an electronics technician, I would never have guessed the problem was electrical if my only experience was mechanical expertise. These newer cars require more in depth knowledge at times, to understand the input and output of system electronics. Some sensors are no longer just a high/low, on/off configuration. They're starting to pulse width modulate signals, meaning that where you thought a single wire was just carrying 12 volts to a sensor, might be multiplexed to carry other signals as well. That complicates things for some mechanics. I never would have guessed this overheating problem with a blown head gasket would lead to a root cause of the main computer voltage regulator.

2002 Pontiac Grand Prix - vibration at 50mph

Car: 
2002 Pontiac Grand Prix 3.8L V-6, automatic transmission
202,000 miles

Problem: 
Owner states the vehicle vibrates at around 50 mph when accelerating. Check engine light on, and tire pressure warning light on.

Test Drive: 
Vehicle begins vibration at about 50mph and continues above this speed. Vibration is a slight side way shimmy, instead of up or down, or front to rear of car when driving. Hard braking from 50mph produces massive shudders throughout car body. When driving at high speed and shifting into neutral to disengage drivetrain, the vibration is not as present as with drivetrain engaged.

Check engine lights produces mass air flow sensor code and egr system malfunction. However, engine is running smoothly, and not stumbling at any speed, or while parked, or in neutral. Fast to low engine idle speed is smooth and no indications of stumbling or hesitation.

Tires were at 25psi. Filled to 35psi and pressed the Tire Pressure Monitor button to calibrate the warning system at 35psi. Test drive again, and vibration is still present.

Visual inspection beneath car and found driver side CV axle inner boot broken, clamp loose. Passenger side CV axle boots in good shape. Check bearing free play and steering knuckle free play, none found in either system.

Checked all motor mounts, and they are in good shape, no tears or worn rubber.

Brake calipers have some free play in them from worn down brake pads, however this doesn't seem out of the ordinary from normal wear and caliper free play, as brake calipers sort of float when brakes are not being applied. Brake pads have 20% life left in them.

Diagnosis: 
Suspect the driver side CV axle, the low brake pad levels to be main culprits which are causing massive vibration above 50mph, and when braking. Also tires are worn, and have 30% life left.

Fix:
1. Replaced driver side CV axle. The original axle inboard boot was torn, and did have some lube left over, but not much. While it was not dried out, rust was present on the roller bearings within the inboard CV joint.

2. Both front rotors turned. The shop technician who turned the rotors indicated the rotors were warped, but were they were able to turn them ant still remain in spec. While most of the rotor was turned true to flat, there was a semi-circular arc that was not touched during the turning process, about 1/4 inch wide at it's widest point. Tech stated that the rotor was indeed flat all the way around despite the half arc present towards the outer edge.

3. New brake pads installed.

4. Front wheels balanced at shop. Each tire required 2lbs of weight to the inside of the wheel rim after removing the original wheel weights from the outside of the wheel rims.

Post work assessment:
Vehicle vibration problem is resolved. No vibration at any speed up to 80 mph. No vibration at any speed with hard braking.