Hello Forum Members,

I have been enjoying my 1994 Dodge Dakota light pickup very much. It was purchased from a well-known neighbor and friend in 2002 with 22,000 miles on it at the time. It is equipped with the 3.9 L V-6 engine. It now shows about 55,000 miles.

Other than a new water pump last spring it has required no major mechanical servicing.

Up until now, starting the vehicle has consisted of getting in, keeping your foot off of the accelerator pedal, turning the key, and BBrroom. It always started on the second good cylinder and it would set up an idle at about 650 RPM and proceed to warm up.

NOW!! Do the same, turn the key and Brroom, it starts but it will not post a good idle, it tries to idle but it dies after about 3 seconds. Acts like you have given it a good primer shot of gasoline that it fires on but then the fuel flow cuts off and the engine dies from lack of fuel. I next opened the air cleaner and gave it a good shot of the ether primer that I use on my lawn tractor engine. The engine then started aggressively and jumped up to 1500-2000 RPM. The engine then died. I tried to tickle the accelerator pedal to maintain that RPM but the engine died as soon as I touched the pedal.

In summary, the engine always starts normally but will simply not establish a good idle so it can warm up and operate normally.

I have a good background as a professional mechanic during my college years and am not afraid to tackle just about anything. It is only all the new engine electronic control systems that leave me scratching my head a bit.

My nephew (with Dakota experience) said I should check and watch the fuel pressure. Does that mean I have to purchase a gauge and attach it somewhere. What do I want to watch for in the pressure gauge if I do that?

Any other ideas or suggestions will be most sincerely appreciated.

Sincerely yours,

Bob Smith biobsmith5@verizon.net

 

I'd check for codes first off. Just because you don't have a check engine light doesn't mean you don't have some codes. There is a write up in the FAQ telling you how to check. Sounds like a sensor to me. Maybe IAC, TPS, or MAP. Oh, and welcome to the forum!

 

it sounds to me like the MAP sensor. But its hard to tell over the internet. it's obviously not the IAC because when you hit the gas pedal, it would have kept running. Also coud be a bad o2 sensor. Like g. man said, check the computer for codes and see what comes up

 

Hello Forum,

Many thanks for those replies. Very interesting.

Well, after a lengthy argument with the FAQ section search engine, I found a post that described the read engine code procedure for a 2000 vehicle. I tried this on my '94 Dakota and my first thought was "How are they going to crank my (mechanical) odometer around to display the engine codes?? Then it occured to me that the later model Dakotas must have digital odometers.

Ok, can anybody tell me where I can rent an engine reader and documentation?? Or some other way to get this critical info.

After much searching of the web, I have discovered IAC, TPS, MAP, and O-2 sensors.
Are there any others I should worry about?

I found what may be the MAP? On my old '94 it looks like a black plastic sphere about 4"-5" in diameter up on the firewall and connected to the engine with what appear to be vacuum hoses.

OK, I waste time and money replacing a good MAP sensor, in what order should I
try the rest?

Can anybody suggest a good vendor of such parts at reasonable prices. I AM NOT going to deal with the local dealer. Made that mistake once already. I like to buy online.

Since engine codes may not be available to me, are there some ordinary tests that I can use to narrow down the problem?

I am a consulting engineer in the fields of electro-mechanical engineering. My office has high quality volt/amp/ohm meters and a good Tektronics scope, misc power supplies, and small computers suitable for industrial applications.

All thoughts and ideas welcome.



Best wishes,

Bob Smith bobsmith5@verizon.net

 

This sounds like an issue I had with my old camaro in which i had to put a new fuel pump in it... any ways here is some info that should be useful to you. good luck

check your fuel pressure. i dont know what your should be at but my 3.9ltr magnum runs between 38 and 44 psi.
Check your external fuel filter.
to check the TPS go here ----> http://www.ehow.com/how_4826645_fix-...n-problem.html

To check the codes stored in the computer:

1. Cycle the ignition key ON-OFF-ON-OFF-ON within 5 seconds. To cycle the ignition key ON means to turn it only as far as it takes to get the radio to come on. It does not mean to turn the engine on.

2. Count the number of times the "check engine" lamp on the instrument panel flashes on and off. The number of flashes represents the code. There is a slight pause between the flashes representing the first and second digits of the code. Longer pauses separate individual codes. For example, flash-flash-flash [pause] flash-flash represents the code 32.

A code of "12" is generally accepted to represent the beginning of codes on our trucks.

A code of "55" represents end of codes. If this is all you get then no error codes are stored in the computer. This is the normal condition.

Code and description
11** Timingbelt skipped 1 tooth or more from initial learned value, Intermittent loss of either camshaft or crankshaft position sensor, No crank reference signal detected during engine cranking
12* Direct battery input to PCM was disconnected within the last 50 key-on cycles (normal)
13** No change in MAP output voltage from start to run
14** MAP sensor output voltage outside the acceptable range (too low or too high)
15** No vehicle speed sensor signal
17* Closed loop temp not reached or engine cold too long
21** 02s sensor does not detect rich or lean condition (signal stays at center)
22** Engine coolant temp sensor signal outside the acceptable range
23** Intake air temp sensor signal outside acceptable range
24** Throttle Position sensor signal outside acceptable range
25** Idle air control motor circuit short or open condition detected
27* Injector control circuit failure
31** Evap Solenoid circuit short or open condition detected
32** EGR Solenoid circuit short or open condition detected
33* A/C clutch relay circuit short or open condition detected
34* Speed control vacuum or vent circuit short or open condition detected OR speed control switch input outside accepted range
35 Rad Fan control relay circuit short or open condition detected (4 cyl only)
37* Torque converter clutch solenoid CKT or park/neutral switch failure
41** Generator field not switching properly
42* Fuel pump relay control ckt, Auto shutdown relay control ckt, No ASD relay output voltage at PCM, Fuel level sending unit volts out of range, Fuel level unit No change over miles
43** Multiple/ single cylinder misfire
44* Battery temp sensor volts out of accepted range
45* Transmission OD solenoid circuit short or open condition detected
46** Charging system voltage too high
47** Charging system voltage too low
51** Fuel system lean
52** Fuel system rich
53* Internal PCM failure
54* No cam signal at PCM
55* End of error messages (If you get this only, no errors were found)
62* PCM failure SRI mile not stored
63* PCM Failure EEPROM write denied
64** Catalytic Converter Efficiency Failure
65 Power steering switch failure

Fault Codes with * - check engine lamp will not illuminate at all times if this code was recorded
Fault Codes with ** - Checking engine lamp will illuminate when the engine is running if this code was recorded

 

Darkknite2009 posted the how to procedure for checking engine codes. Don't know what faq you were in, but doesn't sound like the one for 1st gens. It's located at the top of the 1st gen forum page. Just above this thread.
That is not your MAP, it's the cruise control vaccum actuator. Your MAP is on the throttle body. Look in the FAQ, and there is a diagram showing you where each of these sensors is located.
I just buy my parts at ORielleys. Most parts come with a lifetime warranty. So worst case, I have to take it off and exchange it, but costs me nothing.
There are ways to test the sensors. I just google for the directions when needed. To test the MAP you need a multimeter and a hand vacuum pump.

 

Bob, sounds like a great truck! Once you can get it running right anyway.

Well, I am probably about the last person you might listen to, but I wonder about the fuel filter? With such low mileage, etc., and, one time I had a Nissan truck that kind of acted like you describe, and lo and behold, it was fuel filter!

 

The fuel filter may be in need of replacement.
The fuel pump may be shot, however since your Dak has such low mileage I doubt it.
I'm not sure if this has a specific name, but the linkage that connects the gas pedal to the throttlebody may be a little gummed up (happened to mine), and I just sprayed lubricant onto the cable.
Or perhaps you have a leak in the fuel line. Upon start-up, do you smell any gasoline?

I'm not too keen on fuel systems, but that's just my 2-cents. Hopefully it can help