Left on a 200 mile trip in morning at 75 degrees ambient. After a while, turned on AC. No trouble on trip down. On trip back, at appx 85 degrees at 75 mph on hwy, car felt like it was pulsating, and losing power, eventually, would only run 40 mph. Temp gauge was a little above middle. Stopped, raised hood, looked for anything unusual, found nothing. After 5 or 10 minutes, started car and it drove fine again at 70 mph. After about 50 miles, same thing, pulsating, and car would only go 40 mph. Stopped, looked under hood again, checked water level. Returned to highway, turned AC off, heat on full, with fan on full, and all windows down. drove another 100 miles at 70mph with no issues at all. I think I need a new radiator, but am not aware that performance is affected at slightly above middle level of temp gauge. No check engine light. Any ideas?

Hi,

I found this article by putting in “what is the vapor pressure of gasoline?” I got more than numbers.

https://www.punchlistzero.com/gasoline-boiling-point/

I did this because I know what happens to things that get pumped.
If you study a refrigeration cycle you get tuned in on things like this.
We use a variety of gases “blended” to achieve a certain characteristics of heat removal of the fluid to gaseous state of change. We have low, medium and high temperature rated compressors being used as there are volumetric differences to be dealt with.
Just like the article states, it’s about blends and equipment.

You can trust me on this as Volvo engineering would not put in two pumps if it wasn’t necessary.
Bean counters are all over the place.

Major things that do change are the environments surrounding tanks. They change in levels or amounts contained.
These are not a closed system like refrigeration is but its still about temperature and pressure of working fluids.
Imparting energy into a fluid will affect both of these items.
The pumping action does exactly that.
The main pump actually circulates more fuel than is needed and it goes back to the tank.
You don’t have to guess where those gasoline lines just came from, up front, to know that things are in dynamic phase of changes going on in the system.

So what the tank gets back, is different all the time. Just as much as the environment changes.
The in-tank pump was put there to compensate for this, as the main pump does not like cavitations of any kind.
The injectors issue out what ever they get or don’t get.
The fuel management system can only compensate so much.
It claims to be self tuning but that’s under laboratory built conditions, with all of the components working, to its creators design.

That little pump is a back up for the variables.

Hope this helps all of us to give credit to the engineers and ourselves, for maintaining these cars over the years, despite quality changes that you are noticing.

Phil

Well.... I am not sure I understand all of what you said, but I have come to believe that Engineers are smarter than shade tree mechanics that often disparage them. Also, I have given up on the idea that I will understand all of the components of an automobile. Sometimes, one has to just repair what doesnt work, clean grounds and connections, etc., which often gets you rolling happily down the road. Thanks for the tech. info.

I suffered overheating during a road trip but did not suffer the lose of power, though I did not push it.

I did as you did turning on the heat and opening windows. With that I noticed that the faster I went the higher the temp gauge went, so I kept it down below 50mph for the remainder of the trip.

There are things going on in the dash gauge that modify the temp reading so it does not fluctuate unless extreme and then there is the temp sensor that may not be working 100% to tell the gauge the coolant is too hot.

I found the coolant thermostat was not opening fully. Take it out and put it into a pot of water and bring the water to a boil. You should see the valve open all the way.
--
1988 244 DL; B230F; LH-2.2; Manual 5-speed (M47)

Hi all,

Interesting post about the loss of power so intermittently.
I started think of a failing AMM or throttle switch that changed information going to the ECU.
I don’t know if an AMM can fail intermittently though. Maybe a corroded pin on either one might be worth looking into.

Heck, maybe it’s a bad fuse to the pump itself I thought. Art has lots of experience with the tank pumps and circuits. There have been some horrible pictures of the tank tops from salt invasions.

With the a/c on, that would vary the heat gauge upwards probably the width of the pointer needle but the turning on of the heater core should have affected that back to normal.
With Having the heater on, when you didn’t need it, probably had you keeping your eyes on that gauge, I bet. (:). That is the thing to do when you see a warmed up gauge above normal to check if the radiator is not efficient enough or a thermostat issue developing.

If the ECU senses a heat issue way above normal it will adjust the ignition timing but a loss of power shouldn’t be one of them so far as the limp mode.

Now talking about a happenstances.
I was under my 1992 yesterday spraying on some under coating onto the underside of the footwells. I got a little bit carried away with using up two cans of the rubberized stuff.
When I got back towards the fuel pump, It was then, that I noticed that there was a Schrader valve stem sticking out at me from the inlet line to the main pump.
I had forgotten that I had seen it before shortly after buying the car from the Wagonmeister out here in California.
I know it’s not a standard thing for these to be on a Volvo so maybe he put one on or the previous owner, to him, install it?
It tap out looks to be nicely done. Maybe it’s an available standard part from someone in the Volvo world of modifications.

I think its a nice idea to have it so a person can conveniently check the output of the in-tank pump.
You know, Take a pressure reading or take the core out and see if the flow with bubbles or not.
It might help diagnose the rubber connector hose from sender to the pump. Especially with a lower filled up tank of gasoline too.


Did Volvo or the dealerships install these at one time?
The cap seems very much like the ones use on the fuel rails. Rather slim and tiny to grip but it sticks out so you can get on to it. Not like the stupid one on the fuel rail.

That’ll be it for my thinking challenge. (:-)

Phil

Update of this issue. Different 1989 245.
100 degree ambient, 1/2 tank gas, car ran great, but after a while, it would barely go 20 mph. Stopped car, sat for 5 minutes, then car ran great again.
On principle, ( because car had largely been sitting for 10 years ), I removed in tank pump. Pump frozen, filter "gone", rusted sender pump assembly. Replaced pump, both filters. Car ran great, even at 75 mph from Dallas to Austin at 100 degree ambient.
I do not know why the car would run great with a bad pump, UNTIL IT GETS HOT. This is the same problem I had with the previous 1990 240.
If your 240 develops problems when it gets hot, check in tank pump first. And as
has been pointed out, noise does not confirm proper function.
PS I have no confidence in the in tank pumps available now. I have replaced more than one that looked like new, one after 3 weeks.

Amen. High season for it too.
--
Art Benstein near Baltimore

Airtex E8778

"Did Volvo or the dealerships install these at one time?"

Beginning in '92 both the fuel rail and the tank pump output got Schrader valve test points. It is on the bill of materials.
--
Art Benstein near Baltimore

In 1980, the Winchester drive was born; based on a model from 1973. IBM introduced the 3340 "Winchester" disk system, the first to use a sealed head/disk assembly (HDA). Almost all modern disk drives now use this technology, and the term "Winchester" became a common description for all hard disks, though generally falling out of use. Project head designer/ lead designer Kenneth Haughton named it after the Winchester 30-30 rifle (initially called the "30-30" because of its two 30 MB spindles).

Symptoms describe those of failed fuel delivery from the tank to the main fuel pump. Common reasons for that are:

1. Fuse 4 open or not making good contact.
2. Tank sender feedthrough open.
3. Tank pump inop.
4. Hose from tank pump to sender outlet torn.

In my experience, car runs well and coolant temp looks better after refueling from the cool underground tanks. Runs poorly at higher elevations.
--
Art Benstein near Baltimore

In The Tank

I got my stethoscope out this morning, and can hear the in tank pump running.
How do you account for the improvement in performance after stopping, and after turning the heat on? I have had 240s heat up with no loss in performance. Perhaps I am looking in the wrong direction?

"How do you account for the improvement in performance after stopping, and after turning the heat on?"

In my mind, without you telling us different, you stopped at a filling station and put cool fuel in it. Or coincidence if the tank pump is intermittent and the brushes are short.

I've not heard of any performance loss because of a cooling system malfunction, but a loss of performance caused by lean mixture might result in more difficult cooling.

Also, hearing the tank pump working is no assurance the main pump is getting fed, but I'm sure your listening around would have pegged the raucous cavitation symptom that results. I wonder how many times we all wished our EFI cars had a fuel pressure gauge on the instrument panel to augment the coolant temperature gauge.
--
Art Benstein near Baltimore

Just found 2 lumps on my car battery.
Had them tested.
One came back positive.
Hope it's not terminal

It is a 1990 245.