I recently bought a classic 1981 Dodge Ram D150 Slant V6 in October of 2009 and it was in great shape given the age. Now that I'm finished with graduate school I would like to try to preserve the vehicle as budgets and time allow.

I'm venturing into new territory as I'm not super familiar with engines (old or new).

Here is my first issue:

After leaving the country for 10 weeks for work, I return to start the truck but with no success. After spraying some starter fluid in the air intake the engine appeared to run and sputter on the fumes. It felt like the engine wasn't getting gas.

I separated the fuel line in between the fuel filter and carburetor and it was dry. After many attempts over several days and replacing the fuel filter, there seems to be gas in the line now and the engine will start (only with starter fluid) and will run anywhere from 5-40 seconds.

Engine behavior before the period of inactivity:

If I hadn't driven the truck in a week it would take 2-3 tries to get the engine to start. Say if I would drive and start the engine every other day, it would start right up. I usefully pump the gas 2-3 times when I first jumped in the truck just before attempting to start.

Routinely, once the engine would start (both either in Winter and Summer–Ohio weather) it seemed to idle high until I accelerated from the parked position. From there after it would idle normally during the drive.

Current thoughts and a call for help:

With no experience with working on engines and from doing a little reading online, I'm thinking there may a fuel pressure issue. Before the truck sat a long period it would start and idle pretty high. After the long period of sitting, when I can get it to start for just a bit it idles low and seems to struggle.

Could these symptoms of a failing fuel pump? Or could it be an issue with the spark system? Could it be the carburetor?


Thanks in advance for any help or advice!


FYI: the fuel tank is full...

1981 Dodge Ram D150 3.7L 2WD
Overdrive - 4-Speed
120,000 miles

 

Sounds like a fuel pump issue. Remove the fuel line at the carb and direct it into a can or jar. Turn the engine over to check the flow. It should be a strong flow. Did you check to see what was in the fuel filter when you changed it?

 

Thanks SEAL for the help, here's an update:

I separated the fuel line just after the new fuel filter and tried turning the engine over several times and there wasn't any fuel moving through the line. So, I've gone ahead and picked up a new fuel pump in town. I also cut apart the old fuel filter cylinder to see what the filter looked like. I'm not sure what a new one looks like (whether it may be white or yellow when brand new). When I returned the first fuel filter, I learned that I needed one designed for California's emissions standards - so it appears to have a line that runs back to the tank. Is the second line to add extra pressure in the tank, or to double filter the fuel, any ideas?


Old fuel filter:






New fuel filter:





The bottom half of the engine on the side of the fuel pump was extremely gunky from a long period an oil leak. Before trying to remove any parts, I've tried to clean up the engine block a bit.

Oily engine block & fuel pump:









Just before I removed the fuel pump, I noticed this wire (dead center, hanging over the fuel pump) that was not attached to anything. It has a short wire, so it much attach to something close by... any ideas?

Mystery wire:



Fuel pump removed from engine:






The old fuel pump was made in Canada and had a manufacture date of 1994, so I assume this was replaced before.

Old fuel pump with new fuel pump:






I wanted to share the condition of the fuel lines because I'm not sure if the exterior rust is normal or excessive and wondering if maybe they should be replaced?

Fuel lines from the input of fuel pump back to the tank:



(rubber tubing from fuel pump meets the metal tubing in frame)


(rubber tubing from fuel pump meets the metal tubing in frame - another view)


(further down the frame)


(first bend mid-frame)


(second bend mid-frame)


(lines separating before crossing over truck bed)


(making the bend across the bed)


(just before tank)


(just before tank - another view)


(crossing on top of tank)



Thanks for reading, taking a look at the images and for any help!

 

If the fuel pump corrects the problem and the lines are not leaking I would not change the fuel lines. If the pump doesn't fix it I would look for a collapsed fuel line on the suction side of the pump.

As for inside the filter, what you are looking for is black rubber particles that would show a deteriorating pump diaphragm or hoses.

As to the mystery wire, that is a condenser that was probably wired to the coil as a radio noise suppresser.

I am not smart enough to figure out all the pin headed reasoning that went into the California emissions systems but I do know when you modify them you can create problems so I would stay stock there unless you understand and remove all of it. Fuel pumps are positive displacement diaphragm style pumps and the regulated fuel return line is probably there to prevent over pressurization and resulting fuel vapors from escaping.

Since you cleaned the engine probably using solvent and water, I would make sure inside the distributer cap is dry.

 

Thanks SEAL for the wisdom and help!

I replaced the fuel pump this weekend and with a little help of starter fluid for the first start it's been working great.

I've noticed that the engine doesn't idle really high immediately after startup (it used to always do this in the several months that I've owned the truck) and it also idles significantly lower in general. The dash cluster doesn't have a tachometer so I'm not sure what the RPMs the engine is running at during idle. I'll post a video of the engine idling to see if you guys think it's OK or too low.

New fuel filter & pump in place:










Final cost and parts:

• Fuel Filter: $4.49
• Airtex Fuel Pump: $29.99
• Permatex Liquid Sealer: $3.49
• Engine Degreaser: $3.59
• Starter Fluid: $2.99
• Hose Clamps: $2.49
• Engine Oil: $16.99
• Oil Filter: $3.99
• Tax: $4.59

Total: $72.61

Estimated time: 6-8 hours
(from trouble shooting, to research, cleaning local engine area, replacing parts and cleanup)

Video of engine idle:

http://www.youtube.com/watch?v=yRW89k9t9hw


Helpful links:

How does an mechanical fuel pump work?
http://www.secondchancegarage.com/public/535.cfm

Mechanical fuel pump basics:
http://www.aa1car.com/library/fuel_pump_mechanical.htm

DIY Fuel Pump:
http://autorepair.about.com/cs/doity.../aa093000a.htm




(this appears to be up-side-down compared to its position on the v6 block)