Engine continues to run Cold

[Original77]

I need some help. Ever since I changed my mechanical fuel pump to an electric one, my engine runs cold (130' to 140' degrees) Today I put in a 195' degree thrermostat to see if that would do the trick, no luck. I know the mechanical pump was creating a ton of heat, due to the vapor lock conditions I was experiencing. When I changed that out to an electrical fuel pump my vapor lock problems went away, but now the motor runs too cool. Could it be the radiator cap, the heater only pumps out luke-warm air. I am taking the temp reading off the gauge and off an infrared temp gun, they are the same. I guess I could put some cardboard in front of the grill to limit the amount of cold air thats drawn in. What do you think, thanks for any replies. O'77

 

[mxpaz]

I will take a guess and say check your timing.

 

[72bronco]

I'm stumped. I can't imagine how changing the fuel pump would cause your engine to run cool. ?:? Dumb question, but are you certain that you installed the thermostat in the right direction? If your heater is not blowing hot then your engine is definitely running too cool. Also, I have a mechanical fuel pump and I'm not aware of any heat related problems that would cause vapor lock. It sounds like you have some other sort of problem either related to your thermostat or water pump. Timing could also affect engine temp but I don't think that it would cause it to run that cool, plus if it was that far off it probably wouldn't run well anyway. Then again, if your timing is off you could be experiencing sputtering at certain engine speeds that might seem like vapor lock. Check your timing and let us know where it is set.

 

[Jeepster]

I'll go along with the train of thought here and would consider touching opon one of the basic steps of engine performance namely timing. The method I prefer ( especially on older vehicles with questionable history) is to employ the vacuum gague/tach method instead of the timing light. The engine will tell you whats right that way as far as timing goes.

 

[Explore74]

I'm with jeepster here. There are only 2 ways(short of tearing the engine down) to tell what shape an ingine is in, and how well it is tuned. #1 cylinder blow-down(when engine is shit off of course) #1 manifold vacuum checks. I doubt that the fuel pumps have anything to do with your problem. Have you tried blocking airflow to the radiator with a piece of cardboard to get it heated up? If you can get it heated yp, does the temp immediatly come down when it is removed?

 

[72Sport]

Your heater control valve maybe leaking water and your heater core is providing enough cooling to keep the engine from running on the thermostat, especially in Denver. After the engine has cooled off to about 75 degrees, push the heater temperature knob in all the way. That should close the heater control valve all the way. Start up the engine and see if you can feel a difference in temperature between the engine side of the valve and the heater side of the valve as the engine warms up. If they are the same your temp control valve is leaking and may be keeping the engine cool enough so that it never runs on the thermostat. The engine side of the valve should get hot enough that you can't hold on while the other side should be relatively cool to the touch. <br><br>The mechanical fuel pump will get hot from both the hot water going through the timing cover and the hot oil splashing on arm that contacts the eccentric on the cam. Ford designed them to get hot. <br><br>Vapor lock is caused by a gas line too close to a heat source : exhaust manifold or pipe or in the hot air stream from the radiator. Some books say always run gas lines and mount fuel filters on the outside of the frame if possible or maybe a little one on the carburetor like Ford did. You should not have a vapor lock problem this time of year, especially in Denver. I would bet on a worn out stock pump. <br><br>I think that is about $.02 worth. Good luck.

 

[rulebreaker]

I'll trade ya my overheating problem for your too cool problem!

 

[Waverous]

Have you confirmed you really are running too cold? I mean the fact that you changed a fuel pump and your engine running cold may not be related. Instead, drive the Bronco till it SHOULD be at operating temp and use a thermometer in the radiator to confirm the actual temp. Could be you have a faulty temp gauge or sending unit.

 

[Jeepster]

[quote author=Original77 link=board=5;threadid=12663;start=0#94576 date=1041021484]<br> I am taking the temp reading off the gauge and off an infrared temp gun, they are the same. <br>[/quote]<br><br>infrared temp gun.....say no more

 

[Waverous]

I know I know - Infered temp gun, but I still would like to "see" an actual reading off a thermometer, especially in this situation

 

[ca1a73]

Well I have the same problem. In the summer my motor ran between 180-210. Now that it has been cold under 35degrees, My motor barely goes over 150. I thought the thermostat was stuck. I tried the cardboard in front of the grill, and that worked. But as soon as i stopped, the temperature seemed to drop rapidly. What would cause this? Could it be my timing? The motor seems to run ok....backfires once if i really step on it at low rpms....is this a sign of bad timing?

 

[Jeepster]

[quote author=ca1a73 link=board=5;threadid=12663;start=0#94787 date=1041097854]<br> The motor seems to run ok....backfires once if i really step on it at low rpms....is this a sign of bad timing?<br>[/quote]<br><br>Could be, or carb adjustment on the backfiring. Wouldn't hurt to check it out. Simple thing to do.

 

[ca1a73]

Its an 87 302 fuel injected....no carb.

 

[Explore74]

ca1a73:<br>If you are running an efi motor, have you changed or adjusted the timing? If so, did you short across a timing connector? I'm not too familiar with the EEC family of controls, but almost all computer control requires that you take the computer out of the timing loop by means of some type of jumper. You then set the timing to the correct spec. A backfire sounds like severely retarded timing on an efi engine, and if you set the timing without removing the computer from the timing loop, you could possibly be running in the neighborhood of 10 deg. BTDC. This would also make it run cold and rich, because the majority of fuel is delivered after the spark has been fired.<br><br><br><br>

 

[76Broncofromhell]

I would much rather be at 160 than 220. But then again this 302 gets cranky below 180. Hopefully the 408 will be a little bit smoother up until operating temperature. How does a high compression motor run in cold weather? Not saying I will ever see weather below 40 but still I want to spin snow donuts in Tahoe.

 

[Original77]

I'll check my timing. I also cut my catalytic converter off around the same time that I switched from my mechanical fuel pump to my electric one. Nothing changed too much then, but I shoulda checked the timing after that "upgrade" and didn't. The cardboard in front of the grill gets me up to about 160 degrees, but thats about it, I've also tried disconnecting the fresh air intake from the air cleaner housing seeing if I could scrounge a few degrees and there isn't much difference. Thanks for the replies. O'77<br><br>BTW-Going to an electric fuel pump exclusivly did cure my vapor lock problems. I would suggest anyone experiencing similar trouble, try the electric pump route, it works.